Iisued  June  30,  1913. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— Bulletin  *65. 

A.  D.  MELVIN,  Chief  ok  Bureau. 


THE  MANUFACTURE  OF  CHEESE  OF 

THE  CHEDDAR  TYPE   FROM 

PASTEURIZED   MILK. 


BY 


J.  L.  SAMMIS,  PH.  D., 

Associate  Professor  of  Dairy  Husbandry,  College  of  Agriculture, 
University  of  Wisconsin, 

AND 

A.  T.  BRUHN, 

Expert  Cheese  Maker,  Dairy  Division, 
Bureau  of  Animal  Industry. 


WASHINGTON: 
GOVERNMENT  PRINTING  OFFICE. 

1913. 


\mkch  d  Jun 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  165. 

A.  D.  MELVIN,  Chibf  of  Burbau. 


THE  MANUFACTURE  OF  CHEESE  OF 

THE  CHEDDAR  TYPE   FROM 

PASTEURIZED   MILK. 


BY 


J.  L.  SAMMIS,   PH.  D., 

Associate  Professor  of  Dairy  Husbandry,  College  of  Agriculture, 
University  of  Wisconsin, 

AND 

A.  T.  BRUHN, 

Expert  Cheese  Maker,  Dairy  Division, 
Bureau  of  Animal  Industry. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1913- 


THE  BUREAU  OF  ANIMAL  INDUSTRY. 


Chef:  A.  D    Miiun 
Attittani  Chief:  A    M     I'm 

chief  Clerk:  I  b  uu  i  -  C  Cabbou 

Animal  Butbandrff  Division:  Gi  oboi    M    Rommel,  chief. 

-  on:  M    I  »■  ►bsbt,  i  bief. 
Dairy  Division:   B    11     R  I  M  i  .  «  lii«'i'. 
Field  Inspection  R    \    Ramsay,  chief. 

Iftof  Inspection  R.  P.  Btbddom,  chief. 

Pathological  D  n\    R    MOHLEB,  chief. 

Quarantine  Division:    Ki<  BARD   \\  .  Ill*  KMAN,  chief. 
Zoological  Division:    B     II     RAN80M,  chief. 
Experiment  Station:   E    C.  ><  HBO]  i»i  ft,  superintendent. 
r;  Jambs  M    Pickens 

DAIRY  DIVISION. 

B    H    Rawl,  chief. 

Mm  mkr   Rabilp.  in  charge  of  Dairy  Farming  Investigations. 

8    I     THOMPSON,  in  charge  of  Dairy  Manufacturing  Investigations. 

I      \     RoGl  BS,  >n  charge  of  Research  Laboratories. 

m  charge  of  Market  Mill:  Investigation*. 
Robert  McAdam,  in  charge  of  Renovated  Butter  Inspection. 

2 


LETTER  OF  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Animal  Industry, 

^Yashington,  D.  C,  January  30,  1918. 

Sir:  I  have  the  honor  to  transmit  for  publication  as  a  bulletin  of 
this  bureau  the  accompanying  manuscript  entitled  "The  Manufac- 
ture of  Cheese  of  the  Cheddar  Type  from  Pasteurized  Milk,  "  by  Prof. 
J.  L.  Sammis,  of  the  College  of  Agriculture,  University  of  Wisconsin, 
and  Mr.  A.  T.  Bruhn,  expert  cheese  maker  in  the  Dairy  Division  of 
this  bureau.  The  work  herein  described  was  conducted  at  Madison, 
Wis.,  in  cooperation  between  the  Dairy  Division  and  the  Wisconsin 
Agricultural  Experiment  Station. 

The  Dairy  Division  has  been  represented  at  Madison  by  L.  D. 
Bushnell,  Alfred  Larson,  and  Miss  Alice  C.  Evans,  bacteriologists,  in 
succession;  S.  K.  Suzuki  and  E.  F.  Flint,  chemists,  and  J.  W.  Moore, 
F.  W.  Laabs,  and  A.  T.  Bruhn,  expert  cheese  makers,  in  succession, 
all  of  whom  have  assisted  at  various  times  in  this  work.  The  Wis- 
consin Station  has  been  represented  by  Prof.  Sammis,  who  from  the 
beginning  has  had  charge  of  the  cooperative  experiments  in  the  manu- 
facture of  the  Cheddar  type  of  cheese  from  pasteurized  milk. 

The  comparison  of  this  cheese  with  that  made  from  raw  milk  by  the 
regular  factory  method  has  been  systematically  and  thoroughly 
carried  out  under  a  variety  of  conditions  by  the  use  of  duplicate  vats 
of  milk,  one  of  these  being  pasteurized  in  each  instance.  During 
1910  and  1911,  especially  in  the  latter  year,  the  new  process  was  per- 
fected and  a  large  quantity  of  the  pasteurized  cheese  was  made  under 
commercial  conditions  and  placed  upon  the  open  market.  The 
results  are  fully  described,  also  the  process  of  making  the  cheese, 
and  it  is  shown  that  the  use  of  pasteurized  milk  is  highly  satisfactory 
and  economical.  As  pathogenic  bacteria  have  been  found  to  survive 
for  several  months  in  cheese  made  from  raw  milk,  the  pasteurization 
of  milk  in  making  cheese  is  also  desirable  for  the  protection  of  the 
health  of  the  consumer. 

Respectfully,  A.  D.  Melvin, 

Chief  of  Bureau. 

Hon.  James  Wilson, 

Secretary  of  Agriculture, 


CONTENTS 


Page. 

Introductory 9 

The  need  for  a  new  method  of  cheese  making 9 

Faults  to  be  corrected  in  milk  for  cheese  making 10 

The  necessity  for  the  pasteurization  of  milk  for  cheese  making 11 

Amount  of  heat  necessary  to  destroy  various  bacteria 12 

Previous  attempts  to  make  cheese  from  pasteurized  milk 13 

Difficulties  met  in  making  cheese  from  pasteurized  milk 14 

Difficulties  overcome  by  acidulation  of  pasteurized  milk 15 

The  pasteurization  process 18 

Pasteurization  in  a  discontinuous  or  "  held ' '  pasteurizer 18 

Continuous  and  ' '  held  ' '  pasteurization  compared 18 

Selection  of  best  temperature  for  pasteurization  in  the  continuous  machine .  20 

Objections  to  higher  temperatures  than  160°-165°  F.  for  pasteurization 23 

Effect  of  pasteurization  on  the  properties  of  cheese  curd 25 

The  different  types  of  continuous  pasteurizers  used 28 

The  acidulation  process 28 

The  standard  acidity  of  milk  for  cheese  making 28 

Comparison  of  different  kinds  of  acid  for  cheese  making 30 

The  proportion  of  hydrochloric  acid  required  daily 30 

Testing  milk  for  acidity 31 

Preserving  the  tenth-normal  solution 32 

Diluting  normal  alkali  to  tenth-normal 32 

Adding  acid  to  milk  after  pasteurization 33 

Calculating  the  amount  of  acid  to  be  added 33 

Preparation  of  normal  hydrochloric  acid  in  the  cheese  factory 35 

General  directions  for  pasteurizing  and  acidulating  milk 37 

Making  ready  to  pasteurize 38 

Starting  and  stopping  the  pasteurizer 39 

Starting  and  stopping  the  acidulator 40 

The  use  of  bacterial  starter  in  the  new  process 40 

The  reason  for  adding  starter  in  making  pasteurized-milk  cheese 40 

A  practical  sterilizer  for  the  cheese  factory , 42 

Preparation  of  the  starter 43 

Method  of  making  cheese  by  the  new  process 45 

General  arrangement  of  schedule 45 

Uniform  proportion  of  color  used  in  1911,  and  rennet  required 46 

Adding  starter,  color,  and  rennet  to  the  milk 47 

Cutting,  stirring,  and  heating  the  curd 48 

Drawing  the  whey,  matting,  cutting,  and  turning  the  curd 49 

Milling,  salting,  and  hooping  the  curd 49 

Pressing  and  dressing  the  cheese 50 

Drying,  paraffining,  and  curing 50 

Branding  and  selling  the  cheese 51 

Testing  cheese  for  moisture  when  dressed  in  the  hoop 52 

5 


0  CON 

Page. 

tS  Of  tWO  J  ears'  trial  of  the  new  method 53 

In.  i.m-.'I  \  it-lil  i.i  <  h. •»•<«•  .,1,1a i i m-«  1  l.\  the  D6H  |                   53 

Apparatus  and  methods  of  stud) 53 

Sean  1 1  i'..r  13  sternal i«-  erron  in  experiments  on  \  Laid  of  cheese 

Shrinkage  before  paraffining,  and  yield  of  paraffined  cheese 

Shrinkage  and  >  teld  of  cured  cheese 62 

The  causae  of  the  increased  j  ield  Erom  pasteurized  milk »,!< 

Til.-  Lossse  "i  ia i  Erom  vat  and  prees 

The  increased  moisture  content  ol  pasteurized-milk  i                73 

Tin-  quality  <>i  pasteurized-mili  cheese 

ad  criticisms  of  pasteurised  and  raw  milk  cheese 

Cheese  cured  at  Madison  at  normal  temperature 7.'. 

Cheese  cured  in  tin-  South t 79 

tired  in  warm  room  at  Madison 84 

Cheese  cured  in  cold  storage 85 

Exceptional  differences  between  the  raw  and  pasteurized  milk  cheese.  86 

Summary  of  discussion  of  -'ores 87 

The  demand  for  pasteurized-milk  cheese 88 

I  » pinions  of  purchasers 89 

The  extra  cost  of  making  pasteurized-milk  cheese 89 

Further  trials  of  the  new  process  in  cheese  factories 90 

Summary 00 

Preliminary  and  comparative  work  with  the  old  and  new  methods 90 

Sum.-  advantages  Erom  the  use  of  pasteurized  milk  and  hydrochloric  acid..  02 

Outline  of  the  new  method 93 


ILLUSTRATIONS. 


PLATES. 

Page. 
Plate  I.  Outfit  used  in  testing  milk  for  acidity  (Manns's  acid  test)  and  in  testing 

strength  of  hydrochloric  acid  used  in  cheese  making 32 

II.  The  continuous  disk  pasteurizer,  and  apparatus  used  in  acidulating 

pasteurized  milk 32 

III.  The  continuous  "flash  "  pasteurizer,  and  apparatus  used  in  acidulating 

pasteurized  milk 32 

IV.  Transferring  acid  from  full  to  empty  carboy  by  means  of  siphon 36 

V.  Vat  strainer  for  straining  milk  into  receiving  vat 36 

VI.  A  uniform  layer  of  curd,  showing  use  of  curd  gauge 48 

TEXT   FIGURES. 

Fig.  1.  A  combined  sterilizer,  cooler,  and  incubator  for  cheese-factory  starter..  43 

2.  Method  of  marking  cheese 52 

3.  Distribution  of  total  scores  of  pasteurized  and  raw  milk  cheese 78 

4.  Distribution  of  flavor  scores  of  pasteurized  and  raw  milk  cheese 78 

5.  Distribution  of  texture  scores  of  pasteurized  and  raw  milk  cheese 79 

6.  Distribution  of  total  scores  of  pasteurized  and  raw  milk  cheese 81 

7 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  Florida,  George  A.  Smathers  Libraries  with  support  from  LYRASIS  and  the  Sloan  Foundation 


http://archive.org/details/mancheOOusde 


THE  MANUFACTURE   OF  CHEESE   OF  THE  CHEDDAR 
TYPE  FROM  PASTEURIZED  MILK. 


INTRODUCTORY. 
THE    NEED    FOR    A    NEW    METHOD    OF    CHEESE    MAKING. 

Economy  of  time  and  labor  and  improved  quality  and  uniformity 
of  the  cheese  produced  make  the  large  cooperative  factory  more 
profitable  to  farmers  than  the  small  factory,  provided  they  retain 
the  control,  if  not  the  complete  ownership,  of  it.  There  are  two 
objections  sometimes  raised  against  the  replacement  of  four  or  five 
small  cheese  factories  in  a  neighborhood  by  one  large,  better- 
equipped,  better-manned,  and  more  economical  cheese  factory, 
namely:  First,  that  by  present  factory  methods  cheese  makers  could 
not  make  as  good  cheese  from  milk  gathered  over  a  large  territory, 
because  it  would  be  longer  on  the  road  to  the  factory  and  therefore 
would  not  be  so  fresh  as  otherwise;  second,  farmers  object  to  haul- 
ing milk  a  great  distance,  even  to  a  good  cheese  factory. 

The  only  way  to  get  a  large,  first-class  cheese  factory  located  within 
a  short  distance  of  a  sufficient  milk  supply  is  to  centralize  the  latter — 
that  is,  to  keep  as  many  of  the  best  cows  on  every  farm  as  the  land 
will  support.  Until  this  is  done  there  will  be  many  factories  which 
must  draw  milk  from  a  large  area.  Some  modification  of  present 
cheese-factory  methods  is  needed  by  which  milk  from  a  large  territory 
can  be  successfully  handled. 

The  great  amount  of  inferior  cheese  on  the  market  and  the  lack  of 
uniformity  which  characterizes  the  product  of  the  present  cheese 
factory  of  average  size  is  due  primarily  to  the  variable  quality  of  the 
milk  supply  from  different  farms,  especially  as  to  the  presence  of  dirt 
and  bacteria,  which  produce  faulty  flavors  and  textures  in  great 
variety,  and  to  the  variable  ripeness  or  acidity  of  the  milk  received 
from  day  to  day,  depending  upon  the  care  given  to  it  on  the  farm, 
its  age,  etc. 

The  immediate  effect  of  these  conditions  is  that  cheese  makers  in 
their  effort  to  produce  cheese  of  uniform  quality  from  milk  of  variable 
quality  must  necessarily  use  methods  which  vary  from  day  to  day 
and  from  factory  to  factory.  Under  this  system  each  vat  of  milk 
must  be  watched  carefully  at  every  stage  of  its  manufacture,  and  the 

9 


[0  OHEDDAB   <  SBE8I    PROM    PA8TK1  SIZED   MILK. 

cheese-making  process  must  be  hastened,  or  delayed,  or  modified 
ever]  day,  tccording  to  the  cheese  makera1  judgment.  The  yield  uf 
cheese  also  varies  from  da}  to  day.  depending  upon  t lit*  quality  of  the 
milk  and  the  method  used  id  handling  it. 

The  ideal  conditions  for  cheese  making  require  an  absolutely  clean 

and  perfect    milk  BUpply,  and   this  can  not   he  realized   until  methods 

of  milk  production  <>n  the  farm  are  vastly  improved.  In  the  mean- 
time a  process  tor  treating  milk  daily  at  the  factory  bo  a-  to  bring  it 

into  practically  uniform  condition  for  cheese  making  purposes  i- 
needed.  Such  a  process  should  include  means  for  Btopping  the 
ripening  and  the  growth  of  harmful  bacteria,  etc.,  in  the  milk  as  Boon 
a-  it  i»  received  at  the  factory,  in  order  that  it  may  be  ripened  with  a 

clean  starter,  in  a  uniform  manner,  daily.  The  process  should  he 
applicable  t<>  milk  of  any  degree  of  ripeness  which  can  properly  he 
accepted  a--  lit  for  cheese  making  from  a  sanitary  standpoint.     When 

milk  is  thus  brought  by  a  preliminary  treatment  into  uniform  condi- 
tion at  the  factory,  both  as  to  acidity  and  as  to  bacterial  content, 
the  present  variable  and  irregular  methods  of  making  cheese  could 
probably  be  replaced  by  a  routine  process,  operated  upon  a  fixed  time 
schedule  without  variation  from  day  to  day.  As  a  result,  it  is  to  be 
expected  that  the  uniformity,  quality,  and  yield  of  cheese  would  be 
much  improved  as  compared  with  that  obtained  by  the  older  methods. 
In  many  other  lines  of  manufacture  in  recent  year-  preliminary  proc- 
esses have  been  devised  for  bringing  raw  materials  into  uniform 
condition  before  they  enter  the  manufacturing  process,  and  improved 
products,  increased  economies,  and  larger  output  and  profit-  have 
resulted.  It  i-  desirable  that  the  same  general  methods  of  improve- 
ment which  have  been  used  with  success  in  other  lino  be  applied  also 
to  the  cheese-making  industry. 

WILTS    TO    BE    CORRECTED    IN    MILK    FOR    CHEESE    MAKING. 

The  defects  most  commonly  met  with  in  milk,  which  must  be  cor- 
rected by  such  a  preparatory  process  as  that  contemplated,  are  of 
bacterial  origin.  A  variable  content  of  lactic-acid  bacteria  causes 
milk  when  received  at  the  factory  to  exhibit  different  degrees  of 
acidity  and  also  causes  the  subsequent  development  of  acid  in  the 
milk  and  curd,  while  in  the  vat,  to  go  on  at  varying  rates.  On 
unt  of  the  important  influence  which  acidity  has  upon  the  rate 
at  which  whey  is  expelled  from  curd,  as  pointed  otit  in  a  previous 
bulletin.1  it  may  well  be  said  that  this  is  the  leading  controlling  factor 
in  the  manufacture  of  American  Cheddar  cheese.  Therefore  it  is  of 
prime  importance  to  secure  milk  of  uniform  acidity  with  which  to 

.    ....    B    K...  and  Laabs,  F.  \V.     Factors  controlling  the  moisture  content  of  cheese 
Department  oX  Agriculture,  Bureau  of  Animal  Industry,  Bulletin  122.     Washington,  lyiu. 
Seep  29. 


NECESSITY   FOR    PASTEURIZATION.  11 

begin  choose  making,  and  also  to  provide  for  subsequent  acid  de- 
velopment at  a  practically  fixed  rate  every  day  in  order  to  avoid  the 
present  troubles  due  to  irregular  acid  formation. 

Those  bacteria  which  produce  gas  or  tainted,  unclean  flavors  are 
all  too  common  in  milk,  and  are  the  cause  of  much  trouble  in  the 
cheese  factory.  Bacteria  which  produce  diseases  such  as  tuberculosis, 
typhoid  fever,  diphtheria,  dysentery,  etc.,  have  often  been  found  in 
milk,  although  it  is  difficult  to  prove  that  any  person  ever  contracted 
these  diseases  from  eating  cheese.  These  and  other  bacterial  infec- 
tions of  raw  cream  and  milk  for  city  trade  are  usually  combated  by 
pasteurization;  this  is  true,  likewise,  in  butter  making,  and  with  skim 
milk  when  used  for  feeding  stock.  It  seems  reasonable,  therefore, 
that  any  process,  such  as  pasteurization,  which  will  kill  the  acid, 
taint,  gas,  and  disease-producing  organisms  in  milk  would  also  im- 
prove the  quality  of  the  cheese  produced  therefrom. 

THE     NECESSITY     FOR     THE     PASTEURIZATION     OF     MILK     FOR     CHEESE 

MAKING. 

In  view  of  the  possible  presence  of  tubercle  bacilli  in  market 
cheese,  Mohler x  in  1908  recommended  the  "  pasteurization  of  the 
milk  in  order  to  make  the  cheese  perfectly  safe."  Mohler,  Washburn, 
and  Doane  2  prepared  and  studied  cheese  from  milk  to  which  cultures 
of  bacillus  tuberculosis  had  been  added.  They  inoculated  guinea 
pigs  with  such  cheese  at  various  periods  of  time  after  its  manufacture 
and  found  that — 

Advancing  cases  of  generalized  tuberculosis  were  developed  (in  guinea  pigs)  by 
means  of  inoculation  of  cheese  220  days  old,  and  that  slight  tubercular  lesions  were 
caused  by  the  injection  of  an  emulsion  of  cheese  when  261  days  old." 

They  add: 

If  it  is  possible  to  Use  pasteurized  milk  in  the  manufacture  of  cheese  without  injuring 
the  product  a  simple  solution  of  the  problem  is  offered  to  the  cheese  manufacturer  in 
the  process  known  as  pasteurization. 

These  authors  also  give  a  brief  resume*  of  previous  work  on  this 
subject  in  Europe  and  America. 

It  is  evident  that  the  bacillus  of  tuberculosis  not  only  retains  its 
life  but  also  its  virulence  in  cheese  for  a  considerable  period  of  time, 
and  that  cheese  made  from  raw,  unpasteurized  milk  should  therefore 
be  considered  as  a  possible  carrier  of  tubercle  bacilli. 

There  is  a  strong  tendency  at  the  present  time  to  cure  American 
cheese  more  rapidly  than  in  the  past,  so  that  it  commonly  reaches 

i  Mohler,  John  R.  Conditions  and  diseases  of  the  cow  injuriously  affecting  the  milk.  U.  S.  Treasury 
Department,  Public  Health  and  Marine-Hospital  Service,  Hygienic  Laboratory,  Bulletin  41.  Washing- 
ton, 1908.    See  p.  495. 

J  Mohler,  John  R.,  Washburn,  Henry  J.,  and  Doane,  C  F.  The  viability  of  tubercle  bacilli  in  cheese, 
Twenty-sixth  Annual  Report  of  the  Bureau  of  Animal  Industry,  U.  S.  Department  of  Agriculture  (1909), 
pp.  187-191.    Washington,  1911. 


L2  CHEDDAR   0HXX81    FBOM    PABTBUBIZKD    MILK. 

the  consumer  %i  i  leas  ige  ihun  four  months.  It  has  also  been 
Bhown '  thai  practically  all  d.~>  t<«  98  per  <<* 1 1 1  of  the  bacteria 
presenl  in  milk  arc  retained  in  the  oheeae.  These  fact-  Berre  to 
emphasize  the  desirability  of  pasteurising  milk  for  cheese  making. 

An  ordinance  passed  by  the  common  council  of  the  city  of  Chi 
July    13,    1908,  contemplated   the   pasteurization  of  milk  used  for 

Cheese    making,    although    at     that     date    no    practical    method-    for 

making  American  cheese  from  pasteurized  milk  had  been  published. 

The  ordinance  \\  ;i-  B£  follow 

ined  by  the  city  council  of  the  city  of  Chicago,    *    *    * 
;:<>\  2    it  shall  be  unlawful  to  eeU  any  such  cheese  in  the  city  of  Chicago  unleM 
there  !'<•  stamped  on  the  package  in  plainly  legible  Letters  of  not  Leas  than  onen 
inch  type:  "Made  <>!'  milk  an)  bom  cows  free  from  tuberculosa  as  ahown  by 

tuberculin  teat,"  of  "made  from  milk  (or  cream)  pasteurized  according  i"  the  rules 
and  regulations  ,,i  the  department  of  health  <>i"  the  city  ot  Chicago    *    *    *. " 

!     Tin-  ordinance  .-hull  be  in   lull   force  aii<l   effect  from  and  alter  January  1, 

WImI    NT    <>1      HKAI  VRY    TO    DESTROY     fABIOUfl    BAOTBBIA. 

The  question  as  to  what  temperature  of  pasteurization  will  kill 
disease-producing  bacteria  in  milk  is  of  interest  to  the  consumer  and 
all  connected  with  the  bushu 

The    thermal    death    point    of    various    pathogenic   organisms    i> 

already  Well  known.  Kosenau  states  as  a  result  of  bifl  work  and  that 
of  otheis  that  "milk  heated  to  60°  C.  (140°  F.)  and  maintained  at 
that  temperature  tor  two  minutes  will  kill  the  typhoid  bacillus." 
The  greal  majority  of  these  organisms  are  killed  by  the  time  the 
temperature  teaches  1  or  2  degrees  below  the  point  named  and  few 
survive  to  140°  F. 

The  diphtheria  bacillus  succumbs  at  comparatively  low  tempera- 
tures. Oftentimes  it  fails  to  grow  after  heating  to  5.5°  C.  (131  1  . 
Some  occasionally  survive  until  milk  reaches  60°  C.  (140°  F.).  The 
cholera  vibrio  is  similar  to  the  diphtheria  bacillus  so  far  as  its  thermal 
death  point  is  concerned.  The  dysentery  bacillus  is  somewhat  more 
ant  to  heat  than  the  typhoid  bacillus.  It  sometimes  withstands 
heating  ai  60°  C.  (140°  F.)  for  five  minutes.  All.  however,  are 
killed  when  held  at  this  temperature  for  ten  minutes.2 

In  1904  Russell  and  Hastings3  found  that  the  tubercle  bacillus  is 
killed  by  beating  at  71°  C.  (160°  F.)  for  one  minute. 

From  the  foregoing  it  is  clear  that  pasteurization  at  71°  C.  (160°  F.) 
lie  minute,  and  in  most  cases  for  a  shorter  period,  is  effective  in 

»Sant:  tamkj    B    K  .  raj  Eaabs,  F.  W.     Factors  controlling  the  moisture  content  of  cheese 

r!ment  of  Agriculture,  Bureau  of  Animal  Industry,  Bulletin  122.     Washington,  1910. 

Milton  J.     The  thermal  death  points  of  pathogenic  microorganisms  in  milk.    U.  S.  Treasury 
ii.iit,  Public  Health  and  Marine-Hospital  Service,  Hygienic  Laboratory,  Bulletin  56,  pp.  6S3-686. 

1  Ku>  .ni  "fVtl*.  1     <..     Effect  of  short  periods  of  exposure  to  heat  on  tubercle  bacilli  in 

milk.  Wisconsin  Agricultural  Experiment  Station,  Twenty-first  Annual  Report  (1904),  pp.  178-192.  Mad- 
Uon,  1904.    See  p. 


PREVIOUS   ATTEMPTS   WITH    PASTEURIZED    Mil  K.  13 

destroying  pathogenic  bacteria  in  milk  and  preventing  their  nit  ranee 
into  cheese. 

Babcock  and  Russell,1  from  their  experiments  upon  the  thermal 
destruction  of  galactase,  state  that  "heating  the  enzym  solutions  for 
10  minutes  at  76°  C.  (169°  F.)  suffices  to  destroy  the  digestive  fer- 
ment galactase,  and  even  at  71°  C.  (160°  F.),  for  the  same  exposure, 
its  action  was  materially  reduced."  It  seems  likely,  therefore,  that 
an  exposure  to  160°  F.  for  1  minute  or  less  in  the  continuous  pas- 
teurizer would  not  greatly  weaken  the  action  of  this  enzym  in  milk 
for  cheese-making  purposes.2 

Much  less  attention  has  been  paid  by  bacteriologists  to  the  thermal 
death  point  of  those  bacteria  in  milk  which  produce  gas  and  tainted 
flavors  in  cheese.  Moore  and  Ward  3  have  described  a  gas-producing 
bacillus  isolated  from  milk  and  from  gassy  cheese  which  "is  destroyed 
in  freshly  inoculated  small  tubes  of  bouillon  when  exposed  to  a  tem- 
perature of  60°  C.  (140°  F.)  for  10  minutes  in  a  closed  water  bath." 

It  is  to  be  hoped  that  in  the  future  investigators  will  determine 
also  the  minimum  temperature  required  to  kill  various  species  of 
milk  bacteria  with  an  exposure  of  1  minute  or  less  as  in  the  continuous 
pasteurizer. 

PREVIOUS  ATTEMPTS  TO  MAKE   CHEESE   FROM  PASTEURIZED  MILK. 

The  possibility  of  making  American  cheese  from  pasteurized  milk 
has  been  studied  at  several  experiment  stations  and  elsewhere.  The 
two  difficulties  met  with  are: 

First,  the  fact,  long  known,  that  heated  milk  coagulates  slowly 
with  rennet,  giving  a  loose,  spongy  curd  which  is  not  suitable  for 
cheese  making  because  it  is  too  fragile  to  be  handled. 

Second,  pasteurization  causes  curd  to  expel  whey  more  slowly 
than  otherwise. 

In  order  to  restore  the  coagulability  with  rennet  to  pasteurized 
milk,  Klein  and  Kirsten  4  in  1898  added  calcium  chlorid  and  a  bac- 
terial starter  and  were  able  to  obtain  fairly  good  limburger  and  other 
soft  cheeses.  They  used  for  100  kilograms  of  skim  milk  100  to  125 
cubic  centimeters  of  a  solution  containing  in  100  c.  c.  40  grams  of 
calcium  chlorid,  corresponding  to  20  grams  calcium  oxid. 

1  Babcock,  S.  M.,  Russell,  H.  L.,  and  Vivian,  Alfred.  Properties  of  galactase:  A  digestive  ferment  of 
milk.  Wisconsin  Agricultural  Experiment  Station,  Fifteenth  Annual  Report  (1898),  pp.  77-86.  Madison, 
1898.     See  p.  82. 

2  Kastle,  Joseph  H.,  and  Roberts,  Norman.  The  chemistry  of  milk.  U.  S.  Treasury  Department, 
Public  Health  and  Marine-Hospital  Service,  Hygienic  Laboratory,  Bulletin  56,  pp.  315-417.  Washington, 
1909. 

3  Moore,  V.  A.,  and  Ward,  A.  R.  An  inquiry  concerning  the  source  of  gas  and  taint  producing  bacteria 
in  cheese  curd.  New  York  (Cornell)  Agricultural  Experiment  Station,  Bulletin  158.  Ithaca,  1899.  See 
p.  236. 

*  Klein  and  Kirsten,  A.  Versuche,  betrerlend  die  Wiederherstellung  der  Verkasumgsfahigkeit  erhitzter 
Milch  durch  Chlorcalciumzusatz.  Milch-Zeitung,  vol.  27,  no.  50,  pp.  785-787,  Dec.  10;  no.  51,  pp.  803-805, 
Dec.  17.  Leipsic,  1898.  See  also  Fleischmann,  W.  Lehrbuch  der  Milch wirtschaft.  4th  edition.  Leipsic, 
1908.    See  pp.  304,  305. 


14  CHEDDAB  OHEEfi]     FBOM    PASTBUBIZBD   MILK. 

J 1 1  Denmark  i  kind  of  cheese  is  made  from  pasteurized  skim  milk 
to  which  about  10  i>»t  <«'nt  of  buttermilk  is  added  bo  as  to  l>riii<r  the 
acidity  up  to  about  0.21  per  cent  just  before  adding  rennet.1 

In  1907  Dean  stated  ss  a  result  of  experiments  in  the  use  of  cal- 
cium chlorid  with  pasteurized  milk  for  cheese  making  "the  <• 
uhim  *  as  of  a  soft ,  weak  nature  and  the  cheese  tended  to  be  soft  and 
porous."  He  also  added  \\  to  3  per  cent  of  bacterial  starters  to 
milk  pasteurized  at  is<»  F.  and  ripened  some  time  before  adding 
rennet.  The  rennet  coagulated  the  milk,  but  the  curd  was  weak  in 
body.     He  noted  an  increased  yield  of  cheese,  but  the  cheese  tended 

to  be  <-|>en  and  Weak  in  body  and  texture.      He  adds: 

( >n  the  whole  the  results  art-  not  very  satisfactory  and  ire  shall  require  more  light 
on  the  subject  of  making  pasteurised  milk  cheese  before  we  could  recommend  the 
:  to  Canadian  cheese  makers. 

In  1010  C.  A.  Publow1  mentioned  briefly  some  experiments  in 
making  cheese  from  pasteurized  milk,  adding  to  each  100  pounds  of 
milk  2  cubic  centimeters  of  a  25  per  cent  BohltioD  of  calcium  chlorid 
and  2  or  3  pounds  of  bacterial  starter.  The  details  of  the  method 
and  the  opinions  of  cheese  judges  other  than  the  author  respecting 
the  product  are  not  published.  At  this  station  in  previous  years 
efforts  have  been  made  to  obtain  good  American  cheese  from  pas- 
teurized  milk  with  the  aid  of  calcium  chlorid.  hut  without  success. 

DIFFICULTIES   MET   IN    MAKING   CHEESE   FROM    PASTEURIZED   MILK. 

Pasteurization  of  milk  prevents  or  greatly  delays  subsequent 
coagulation  with  rennet.  The  curd  from  such  milk  when  finally 
eut  into  cubes  expels  moisture  with  much  greater  difficulty  than  a 
raw-milk  curd,  probably  because  of  some  chemieal  change  produced 
in  the  casein  by  the  heat  of  pasteurization.  Rapid  acid  formation 
by  bacterial  action  which  occurs  in  raw  milk  and  raw-milk  curds 
does  not  occur  in  the  pasteurized  material.  The  presence  of  a  mod- 
erate amount  of  Lactic  acid  in  raw-milk  curds  greatly  hastens  the 
separation  of  whey  from  the  curd,  and  the  lack  of  acid  development 
m  pasieuiTzed-milk  curds  is  another  condition  favoring  the  retention 
of  excessive  moisture  in  the  curd  and  che< 

The  addition  of  calcium  chlorid  to  milk  which  has  been  pasteurized 
18  known  to  restore  in  a  measure  the  coagulability  of  (he  milk  with 
rennet,  but  we  have  observed,  as  Publow4  points  out.  that,  although 
coagulation  begins  in  about  live  minutes,  "the  curd  does  not  beeome 
linn  enough  for  cutting  in  the  usual  time  and  should  not  be  cut 
before  it  i*  linn."      Although  the  addition  of  calcium  chlorid  restores 

.king,     oth  edition.     Madison,  Wfc.,  1900.     See  p.  194. 
•  Dean.  EL  U.     BxpflriDttDtl  in    cheese  making.     Ontario  Agricultural  College,  Thirty-third   Annual 

;      130. 
»  Publow,  Charles  A.     Fancy  ObMM  fan  America.    Chicago,  1910.     See  p.  20. 
1  Lo  U, 


DIFFICULTIES   OVERCOME    BY   ACIDULATION.  15 

the  coagulability  with  rennet,  it  does  not  correct  the  acidity  and  the 
other  difficulties  mentioned  above  as  being  caused  by  pasteurization. 
The  lack  of  acidity  in  such  curd  might  be  supplied  by  adding  starter 
to  the  pasteurized  milk  and  ripening  for  several  hours  before  starting 
the  cheese  making,  but  the  resulting  loss  of  time  would  prohibit  this 
practice  in  factories.  Where  both  starter  and  calcium  chlorid  are 
added  to  milk  after  pasteurization,  as  suggested  by  Publow,  and  the 
cheese-making  process  is  begun  at  once  without  waiting  for  ripening, 
the  daily  variations  in  natural  acidity  of  the  milk  used  produce  cor- 
responding variations  in  the  moisture  content  of  the  cheese  which 
affect  its  quality.     (See  Table  1.) 

What  is  needed  in  place  of  calcium  chlorid  for  addition  to  pasteur- 
ized milk  is  something  which  will  not  only  restore  the  coagulability 
with  rennet,  but  which  will  also  bring  up  the  acidity  without  delay  to 
a  sufficiently  high  percentage  to  induce  reasonably  rapid  and  com- 
plete separation  of  whey  from  curd.  A  uniform  acidity  is  necessary 
daily  so  as  to  avoid  daily  variations  in  moisture  content  of  cheese. 

DIFFICULTIES    OVERCOME    BY   ACIDULATION    OF    PASTEURIZED    MILK. 

The  substance  which  has  been  found  to  meet  all  of  the  foregoing 
requirements  and  which  appears  to  be  unobjectionable  from  all  stand- 
points is  Irydrochloric  acid.  While  it  might  appear  impracticable 
at  first  glance  to  acidulate  milk  in  large  quantities  daily  at  a  factory, 
yet  upon  trial  this  is  found  to  be  entirely  practicable;  and  it  has  now 
been  done  almost  daily  for  nearly  three  years,  without  any  trouble 
arising  from  coagulation  of  the  milk  with  acid  at  any  time. 

In  Table  1  is  shown  the  moisture  content  of  green  cheese  obtained 
on  12  days  from  pasteurized  milk  by  the  use  of  calcium  chlorid 
in  the  proportions  suggested  by  Publow  (see  p.  14)  and  by  the 
use  of  hydrochloric  acid,  using  always  sufficient  acid  to  raise  the 
acidity  of  the  milk  to  0.25  per  cent  calculated  as  lactic  acid.  The 
milk  used  in  the  two  vats  was  taken  from  the  same  receiving  vat 
full  of  milk,  after  thorough  mixing.  It  was  all  pasteurized  alike 
and  one-half  was  then  treated  with  calcium  chlorid  and  the  other 
with  hydrochloric  acid.  These  were  then  made  up  into  cheese 
separately  and  were  sampled  for  moisture  at  the  time  the  cheeses 
were  dressed,  after  pressing  one  hour.1  From  the  table  it  can  be 
seen  that  whenever  the  acidity  of  the  milk  used  was  low  (0.16  to  0.18 
per  cent)  the  moisture  content  of  the  cheese  made  with  calcium 
chlorid  was  high  (40  to  44.45  per  cent),  and  when  the  acidity  was  high 
(0.21  to  0.23  per  cent)  the  moisture  content  was  low  (38  to  40  per 
cent).  But  in  all  cases  where  hydrochloric  acid  was  added  instead 
of  calcium  chlorid  the  moisture  content  of  the  card  was  37.5  to  40 
per  cent,  whether  the  natural  acidity  of  the  milk  was  high  or  low. 

i  The  correctness  of  this  method  of  sampling  cheese  for  the  moisture  test  is  demonstrated  in  the  latter  p  art 
ofthisbulietin. 


[6  OHBDDAB       III  M    PASTEURIZED   MILK. 

TABLI  1—  Corn,  IfRl   and  fuMj  of  cheese  made  with  MaMMR 

•   I 


..f  milk 

when 

teur- 

Moisture 

content  of 

Critici  in. 

nade. 

1  I. 
vor. 

ture. 

or. 

Text  tire. 

Ml. 

17 
.17 
.  1 7.". 
.  1 76 
.17", 
.  1 7". 
.17.'. 
.  17'. 
.  1  v.'. 
.  1 B8 
.190 

.190 
.21 

.21 
.21 
.21 

.31 

,lv7 
.21o 

Calcium  chlorid  ... 
Hydrochloric  add . 
Calcium  chlorid . 

Hj  'lrrx'hli.r 
(  allium  chlorid  . .  . 
Bydrochlorl 
Calcium  chlorid . 
H>  drochloric  acid. 
Calcium  chlorid.. . 
Hydrochloric  acid. 
(  aW  lam  chlorid  . .  . 
Hydrochloric  acid. 
Calcium  chlorid..  . 
Hydrochloric  ari-1 
t  alcium  chlorid.. . 

Hydrochloric  acid. 

Calcium  chlorid.. . 

Hydrochloric  arid. 

Calcium  chlorid. . . 

Hydrochloric  acid. 

<  allium  chlorid  .. . 

Hvdrochloric  acid. 

do 

do 

do 

Calcium  chlorid.. . 
Hydrochloric  acid. 

Per  crnt. 

87.70 
13  38 

38.80 
41  BO 

■a:  7ii 

44.27 
39.20 
44  27 
39.62 
44.46 
39.02 
42.90 
39.90 
41.50 

39. 95 
39.  20 
39.62 

38.60 
40.60 
39. 95 
39.  05 

38 
41* 
40 
41 

M 

411 

2| 

17 

41 
411 

41* 
40 

81 
g' 

41 
39 
411 

41 

41 

26 

24 

27 
25 

26* 

25 

26 

27* 

26 

26* 

26* 

17 

26J 

27  | 

Flat,  punpent 

Clean 

Curdv.loo.se,  weak. 
Trifle  , 

juiv  a 

Plat,  Lackinj 

('Iran  and  0.  K  .  . 
acid 

Trifle  add... 

Trifle  weak. 

md  sticky. 
kicky. 

Trifle  weak. 

Do. 

\ >rv  loo-e.  weak. 

Trifle  m 

Stick]  . loo^e,  short. 

Kxu  n 

Do 

1 

Low,  LackJn| 
Trifle    hat] 
Sour-milk  flavor.  . 

Trifle  sharp 

(loan  and  O.K... 
o.  K 

1 

Hitter,  larks  acid.. 
O.K 

Coarse,  loose. 

1 

I'M                ... 

Aup.  i: 

Aup.  11 

P.. 

Aup.  : 
fcug,  Li 

\  hitter 

Acid  aftcrta 



do * 

Vinegar  flavor 

Clean  and  O.  K  .  .. 
Trifle  bitter 

Weak,  mechanical 

holes. 
Mechanical  holes. 
Weak    . 
Loose,  sticky. 

'ides.' 
Trifle  1 

Short,  stickv. 
Trifle  short.' 

38.67 

•i 

42.00 

39. 45 
41.23 

25.  73 



Prom  the  above  table  it  is  evident  that  when  milk  is  acidulated  with 
hydrochloric  acid  after  pasteurization,  as  in  the  new  method,  the 
moisture  content  of  the  green  cheese  is  not  affected  by  the  ripeness  of  the 

milk  before  pasteurization  and  is  quite  constant  between  37.5  and  40 
per  cent.  This  advantage  does  not  attend  the  use  of  calcium  chlorid. 
The  daily  variations  of  moisture  content  shown  in  column  4.  which 
are  between  37.5  and  40  per  cent,  are  doubtless  due  to  causes  other 
than  acidity,  and  did  not  Qoticeably  affect  the  quality  of  the  ch( 
The  BOOree  and  criticisms  show  that  the  cheese  made  with  calcium 
chl<»rid  was  neither  ;:s  uniform  Dor  as  good  in  quality  as  that  made 
with  hydrochloric  acid. 

The  addition  of  hydrochloric  or  lactic  acid  to  cream  to  raise  Its 
acidity  without  delay,  preparatory  to  churning,  was  attempted  by 

Babcock  in  L888.1  The  addition  of  a  commercial  acid  to  raw  milk 
1<>  raise  its  acidity  without  waiting  for  bacterial  action  was  BUggested 
to  the  writer  in  1905  by  Dr.  S.  M.  Babcock.  chief  chemist  of  the 
Wisconsin   Experiment    Station,   and   during  the  years   L905  6  the 

effort  ^n-  made,  following  the  suggestion  of  Dr.  Babcock.  to  avoid 
the  necessity  for  ripening  milk  for  cheese  making  at  the  factory  and 

M      ChurninK  U  mbl   Igrioultora]  Kxperiment  station.  Fifth  Annual  Report, 

-      Sec  p.  IIS.     <er  alto  patent  prantei  to  Mullrr,  Milch-zeitunp,  vol.  M,  no. 
19,  p.  301,  Bremen,  May  12,  UMj    il    >  notes  ,m  this  subject  in  s3me  volume,  pp.  125,  4ft4,  701,  750. 


DIFFICULTIES   OVERCOME    BI    iCIDULATION. 


17 


to  substitute  for  such  ripening  the  addition  of  a  commercial  acid  to 
the  milk  as  soon  as  it  was  received,     [mmediately  after  acidulating 

the  milk  it  was  heated  to  86°  and  rennet  was  added  and  the  process 
completed  in  the  usual  manner.  Those  experiments  slowed  conclu- 
sively that  a  commercial  acid  such  as  bydro<  hloric  a;  id  can  he  added  to 
milk  without  in  any  way  damaging  the  quality  of  t be  <  beese  obtained. 
However,  the  quality  of  choose  obtained  from  overripe  or  tainted 
milk  was  not  improved  by  the  use  of  the  acid,  and  it  was  concluded 
that  acid ulat ion  alone  does  not  offer  sufficient  advantages  to  warrant 
its  recommendation  to  cheese  makers.  The  addition  of  acids  to 
pasteurized  milk  for  choose  making  was  begun  by  the  writer  in  1907. 

Pasteurization  and  acidulation  of  milk  appear  to  be  complementary 
processes,  each  supplying  what  the  other  lacks  and  together  forming 
the  basis  of  an  improved  method  of  cheese  making. 

Since  the  use  of  calcium  chlorid  in  pasteurizod-milk  cheese  will  not 
be  referred  to  again  in  this  paper,  two  other  points  will  be  mentioned 
hero  in  which  the  use  of  hydrochloric  acid  is  more  advantageous. 
Those  are:  First,  that  the  hydrochloric  acid  curds  always  begin  to 
thicken  6^  to  7  minutes  after  rennet  is  added,  while  with  calcium 
chlorid  the  first  visible  coagulation  occurs  earlier  if  the  milk  used  is 
very  ripe  and  later  if  the  milk  is  sweet,  thus  varying  from  day  to  day, 
as  shown  in  Table  2.  Second,  the  percentage  of  fat  lost  in  the  whey  is 
on  the  average  about  0.14  per  cent  greater  in  the  method  using  cal- 
cium chlorid  than  when  hydrochloric  acid  is  used,  as  also  shown  in 
Table  2.  This  is  probably  because  calcium  chlorid  curds  are  always 
more  mushy  and  easier  to  break  up  in  stirring  than  curds  made  with 
hydrochloric  acid.  The  latter  are  really  superior  in  this  respect  to 
curds  obtained  by  the  regular  factory  methods. 

Table  2. — Comparison  of  calcium  chlorid  with  hydrochloric  acid  as  to  their  effects  on  chee&e 

made  with  pasteurized  milk. 


Date. 

Time  required  for 
visible    coagula- 
tion after  adding 
rennet. 

Per  cent  of  fat  in 
whey  at  time  of 
drawing     whey 
and  ma  1 1  i  n g 
curd. 

Acidity 
of  milk 
used. 

Calcium 
chlorid. 

Hydro- 
chloric 
acid. 

Calcium 
chlorid. 

Hydro- 
chloric 
acid. 

1911. 
July   28 
Aug.   11 
16 
17 
18 
22 
23 
24 
25 
28 

Average.. 

Minutes. 
14 
15 

6 

4 
14 
141 
18 
18 
16 
.6* 

Minutes. 
7 
7 
7 
7 
7 
7 
7 
7 
7 
7 

Per  cent. 
0.23 
.35 
.16 
.21 
.32 
.32 
.39 
.42 
.38 
.17 

Per  cent. 
0.13 
.14 
.12 
.14 
.19 
.18 
.20 
.20 
.16 
.13 

Per  cent. 
0.17 
.185 
.21 
.21 
.165 
.165 
.175 
.175 
.175 
.22 

.295 

.159 

79994°— Bull.  165—13- 


Is  OHEDDAB  0HBE8I    FBOM    PA8TEX7BIZED   MILK. 

THE  PASTEURIZATION    PROCESS. 
PASTEURIZATION    I  \    a    DISCONTINUOUS  OB       iu:i.l>"    PASTEURIZES. 


In  M;i\ .  L907,  one  day's  milk  supply  was  divided  in  two  portions, 
one  of  which  was  made  up  by  the  regular  method  and  the  other  was 
pasteurized  for  I"*-  minutes  at  160°  F.  and  acidulated  with  hydro- 
chloric acid.     'Idic  pasteurized  vat  gave  the  best-flavored  cheese  after 

curing,  though  it  was  inferior  in  texture  to  the  other,  (hi  March  12 
and  27,  1908,  milk  pasteurized  at  140°  for  20  minutes  and  then  acidu- 
lated gave  Buch  good  cheese  that  a  systematic  Btudy  of  the  combined 
process  of  pasteurization  and  acidulation  was  begun  in  Jury,  L908. 
Cheese  was  made  from  milk  pasteurized  at  l  lo  F.  for  20  minutes, 
either  in  a  Potts  pasteurizer  <>r  in  the  cheese  vat,  by  ronning  first 

Bteam  and  then  cold  water  into  the  jacket.      At   the  >aine  time  part  of 

t  he  milk  Bupply  after  mixing  and  dividing  was  used  for  making  cheese 

by  the  regular  methods.     The  scores  given  to  the  two  Lots  of  cheese 

thus  obtained  are  shown  below : 

Taule  $.— Comparison  of  flavor  <ut<I  ii  ttwn  ofcheest  made  from  rati  unfit  and  from  milk 
j.asi.  urized  "i  i  \0    !■'  for  10  min  - 


Pasteurized  cheese. 

Regular  make. 

made. 

Texture. 

Flavor. 

Texture. 

1908. 

Julv    1') 

26.2 

36.2 

27.8 

17 

40.0 

27.  0 

-   " 

is 

41.7 

27.  ■". 

20 

40.8 

37.3 

21 

41.2 

41.2 

41.3 

23 

39.5 

24 

41.(1 

•> :.:':. 

81 

10.25 

36.5 

26.5 

40.58 

L'T.on 

3S.30 

26.66 

The,  scoring  was  done  by  J.  W.  Moore  and  F.  W.  Laabs.  In  BVeiy 
case  hut  one  the  pasteurized  cheese  had  better  flavor  and  there  was 
little  difference  in  texture  between  the  two  lots. 


CONTINUOUS    \\l>       HELD       PASTEURIZATION    COMPARED. 

On  account  of  the  Large  volume  of  milk  which  must  be  handled 
daily  in  a  cheese  factory,  and  the  greater  expense  involved  in  providing 
arrangements  of  sufficient  capacity  for  beating  and  cooling  5,000  to 

!  pounds  of  milk  at  one  time  BS  compared  with  the  small  cost  of 
a   continuous    pasteurizer,    most    of     (he    later   work    was   done   with 

continuous    pasteurizers.     These   can    he    used    for    handling    any 
required  volume  of  milk,  a  larger  quantity  simply  necessitating  a 


COMPARISON    OF   CONTINUOUS   AND         HELD         PASTEURIZATION. 


19 


longei  time  for  running.  At  the  present  time  they  are  believed 
preferable  for  cheese-factory  use  over  any  form  of  intermittenl  pas- 
teurizer vet  devised.  Good  results  had  been  obtained  by  pasteuri- 
zation at  140°  for  20  minutes,  but  since  continuous  pasteurization 

Beemed  the  more  practical  factory  method,  it  was  determined  to  use 
both  methods  in  comparison  on  the  same  milk  for  several  days.  On 
eight  days,  between  July  16  and  24,  1908,  half  of  the  milk  was  pas- 
teurized at  140°  for  20  minutes  and  the  other  half  at  either  150°,  160°, 
or  170°  in  the  continuous  machine.  The  effectiveness  of  the  two 
methods  of  pasteurization  was  judged  from  the  increase  in  acidity 
observed  in  the  whey  within  the  time  from  cutting  curd  to  drawing 
whey  specified  in  each  case. 

Table  4. — Increase  of  acidity  after  pasteurization  by  continuous  and  by  held  processes. 


Date. 

Milk  held  at  140° 
for  20  minutes. 

Miik    pasteurized 
at  150°.    Instan- 
taneous. 

Milk     pasteurized 
at  160°.    Instan- 
taneous. 

Milk     pasteurized 
at  170°.    Instan- 
taneous. 

In- 
crease. 

Time. 

In- 
crease. 

Time. 

In- 
crease. 

Time. 

In- 
crease. 

Time. 

1908. 

July  16 
17 
18 
20 
21 
22 
23 
24 

Per  ct. 
0.11 
.068 
.055 
.01 
.02 
.03 
.078 
.018 

H.  m. 

2     57 
2    17 
2    17 
2    31 
2    19 
2     21 
2    10 
2    30 

Per  ct. 

H.    m. 

Per  ct. 

0.  055 

.03 

.03 

H.  m. 
3      0 
2    59 
2    46 

Per  ct. 

H.    m. 

0.01 
.01 
.035 
.053 

3    30 
3    30 
3    20 
3      8 

0.01 

2    40 

From  the  above  it  can  be  seen  that  where  milk  is  highly  inoculated 
when  raw,  as  on  July  16,  17,  18,  and  23,  the  acidity  of  the  whey  rose 
0.05,  0.06,  0.07,  and  0.11  per  cent  in  about  2\  hours  after  pasteur- 
izing at  140°  for  20  minutes,  while  it  rose  only  about  half  as  high  in 
3  hours  after  pasteurizing  at  160°  or  170°  in  the  continuous  machine. 

A  further  substantial  difference  between  curds  from  milk  pasteur- 
ized on  the  one  hand  at  140°  for  20  minutes  and  on  the  other  at  160° 
in  the  continuous  machine  is  that  the  former  curds  often  become  mel- 
low and  greased  on  the  surface  and  leak  white  whey  after  milling,  in 
this  respect  resembling  some  raw-milk  curds.  It  was  supposed  at 
first,  from  analogy  to  ordinary  factory  methods,  that  the  curd  which 
became  mellow  and  somewhat  greased  on  the  surface  and  which  leaked 
more  or  less  white  whey  was  more  likely  to  turn  out  well  than  the 
other,  which  was  supposed  to  be  lacking  in  acid  or  acid-forming 
bacteria.  The  observation  was  made  that  a  curd  from  milk  pasteur- 
ized at  170°  and  afterwards  treated  with  5  per  cent  starter  did  not 
become  mellow  in  the  least,  while  curds  from  the  same  day's  milk 
pasteurized  at  140°  for  20  minutes  and  then  treated  with  three- 


(Ill  DDAR  (ill  I  SE  FROM  PAS!  EUBIZED  MILK. 


fourths  per  cent  starter,  became  very  mellow  and  abundantly  greased 
before  milling.  It  was  j i m Ilt*-« I  unnecessary,  thereafter,  bo  wait  for 
mellowness  or  any  other  evidence  of  bacterial  action  or  acid  develop- 
ment in  a  pasteurized-milk  curd.     If  a  sufficient  proportion  <»f  Btarter 

has  '"•-•ii  ad<lc<|  after  pasteurization,  it  1-  perfectly  certain  that  the 
ii  a  arc  present  in  the  curd,  and  will  take  part  in  the  curing  on  the 
From  this  point  of  view  the  mellowness  which  the  140°  curds 
<.<•<  asionally  exhibit  >s  to  be  regarded  as  objectionable  and  as  evidence 
of  lack  <>f  uniformity  between  different  days'  make,  and  since  this 
n  iver  occurs  with  milk  pasteurized  at  L60c  in  the  continuous  machine 

the     hit  ter     appeals  preferahle. 

The  cause  for  the  greater  increase  of  acidity  in  whey  after  cutting 
curd  from  milk  pasteurized  at  140    for  20  minutes,  a-  shown  al 
i-  in-  doubt  the  fact  that  the  milk  thus  pasteurized  contained  more 
living,    active    bacteria    than    that    pasteurized    in    the   continuous 

machine.      Sample-    were    taken    for    bacteriological    count    in    every 

case  immediately  after  pasteurizing,  and  then  three-fourths  per- 
cent  of  starter  was  added   to  each   \at,   followed   immediately   by 

rennet    as  soon   as   the   vat    could    he   heated.      Bacterial   count-   were 

made  on  these  samples  by  Mr.  L.  D.  Bushnell,   bacteriologist,  as 

follow  - : 


Table. 


Number  of  bacteria  per  cubic  centimeter  in  raw  and  pasteurized  milk. 


Date. 

Raw  milk. 

Pasteurized  milk. 

At  14')°  for  20 
minutes. 

In  continuous  machine. 

1908. 
Julv    17 
18 
30 
21 
22 
23 

21 

Number  per  c.  c. 

102,  (XX),  000 
72. (XX). (MX) 

!HUHX),000 
00,000 

173. (XX). (XX) 

3G0,(x 
66,  (XX),  000 

Number  per  c.c. 
2,306,000 

-O.000 

33,000 

.000 

16,820,000 

62,000 

Number  per  cc. 

-.000 

(.000 

200,000 

9,200 

38,000 

1,300.000 

1,100,000 

°F. 
160 
100 

170 

170 
170 
170 
150 

SELECTION     OF     BEST     TEMPERATURE     FOR     PASTEURIZATION     IX     THE 
(ONI  [NUOUfi    MACHINE. 


The  temperature  -elected  should  be  high  enough  to  insure  that 
the  ri|  ening  of  the  milk  shall  he  uniformly  checked  daily,  regardless 

of  the  bacteria]  content  of  the  milk  used,  and  it  should  not  be  so 
high  as  to  injure  the  quality  of  the  cheese.  Testa  were  made  as 
follow-:  Qd  several  days  the  milk  supply  after  mixing  was  divided 
into  four  lots,  one  of  which  w  a-  made  up  by  regular  methods,  the 
other-  were  pasteurized  at  140°,  150°,  and  1G0°  and  made  up  in 
separate  vats.     The  cheese  after  curing  was  examined  by  several 


r.i.sr    i  i.\iri:i;\  hue  for   r.\srKii{iz.\TKix. 


21 


export  cheese  judges,  Including  Messrs.  U.  S.  Baer,  Etoberl  McAdam, 
H.  J.  Noyes,  K.  W.  Laabs,  and  Gottlieb  Marty,  whose  score-  are 
given  in  Table  6: 

Table  G. — Quality  of  cheesi   made  from  raw  milk  and  from  milk  pasteurized  at  different 
temperatures  in  the  continuouS'disk  machine. 


Date. 

Pasteurized  at— 

140°  F.                   150°  F. 

100°  F. 

Flavor. 

Tex- 
ture. 

Flavor. 

Tex- 
ture. 

Flavor. 

Tex- 
ture. 

Flavor. 

Tex- 
ture. 

1908. 
July    14 
15 
16 
17 
20 
21 
22 
15 

IG 

17 

20 

21 

22 
23 
24 

40.0 
40.5 
38.0 
38.0 
40.0 
41.0 
37.0 

28.5 
28.5 
28.0 
28.5 
28.5 
28.5 
28.0 

41.5 
41.0 
40.0 
41.0 
41.0 
41.0 
38.0 

28.5 
29.0 
29.0 
29.0 
28.5 
28.5 
28.0 

43.0 
41.0 
41.0 
42.0 
42.0 
41.5 
39.0 
41.0 
44.0 
42.0 
40.0 
44.0 
41.5 
38.0 
44.5 
43.0 
40.5 
44.0 
41.0 
40.0 
40.0 
44.0 
37.0 
40.0 
35.0 
43.0 
40.0 
43.5 
36.0 

28.5 
29.0 
29.0 
29.0 
29.0 
29.0 
27.5 
27.5 
28.0 
28.0 
27.0 
28.0 
28.5 
23.0 
29.5 
29.0 
28.5 
29.0 
28.0 
28.0 
27.0 
29.0 
29.5 
25.0 
25.5 
27.0 
28.0 
28.5 
26.0 

40.6 
36.0 
36.0 
38.0 
39.0 
35.0 
38.0 
40.0 
40.0 
38.0 
38.0 
36.0 
37.0 
40.0 
35.0 
37.0 
42.0 
33.  0 
36.0 
37.0 
39.0 
36.0 
42.0 
37.0 
44.0 
36.0 
43.0 
32.0 

28.5 
27.0 
28.0 
28.5 
29.0 
28.0 
27.0 
26.0 
26.0 
26.0 
24.0 
27.0 
26.0 
26.  0 
26.  5 
26.  0 
27.0 
28.0 
28.0 
25.0 
26.0 
28.0 
28.0 
27.0 
26.0 
27.0 
28.0 
28.0 









In  nearly  every  case  the  160°  pasteurized-milk  cheeses  were 
cleaner  in  flavor  and  scored  higher  than  the  check,  and  in  every 
case  they  scored  higher  than  the  cheeses  pasteurized  at  140°  and  150°. 
The  different  judges  scored  the  cheese  at  different  ages,  which  will 
account  for  the  wide  variation  of  some  scores.  Bacterial  counts 
made  by  Mr.  W.  H.  Wright 1  show  that  pasteurization  at  160°  is 
more  effective  than  at  lower  temperatures.  This  is  well  illustrated 
in  Table  7. 


Unpublished  work  by  W.  H.  Wright,  instructor  in  agricultural  bacteriology,  University  of  Wisconsin. 


CHEDDAR    CHEESE    FROM    PASTE1   SIZED    MILK. 


ial  content  of  milk)  Itemperatt  ont'uiuous- 

machine. 


MllllC. 

Milk  i-u-w-urized  at— 

1+J°  r. 

150°  F. 

Jul. 

B 
M 

6,080,000 
1,5-*. 

600,000 

50,000 

11,60 

That  the  use  of  160°  for  pasteurization  is  high  enough  to  kill  most 
of  the  bai  teria  in  milk,  so  as  to  meet  requirementfl  Mich  as  those  of 
(he  Chicago  ordinance  previously  referred  to  on  page  12,  is  shown  in 
Table  S  by  the  following  bacterial  counts  made  by  Mr.  Alfred  Larson 
in  1909: 

Tjlblk  8.— Bacterial  content  of  milk  before  and  after  pasteurization  in  the  continuous- 
disk  machine  at  160*  P 


Date. 

Bacteria  per  cubic  centimeter. 

Decrease. 

Raw  milk. 

Pasteurized 
milk. 

1909. 

Per  cent. 

Aup.   17 

161,600,000 

223,350 

99.8 

18 

43,300,000 

1.275,000 

97.0 

19 

-1,000 

211,600 

99.6 

20 

•<>,000 

21 

20,^ 

99.8 

22 

15,543 

97.0 

24 

SO,  600 

99.0 

26 

44,075,000 

99.8 

27 

70,000,000 

99.9 

28 

05,000 

166,460 

99.8 

31 

148,200,000 

99.9 

Sept.    1 

-       ..IKK) 

99.9 

2 

99.9 

14 

50,000 

99.9 

10 

'  1,606 

341.606 

99.6 

17 

38, 91  - 

99.6 

18 

124,766,660 

19 

99.5 

•Jl 

185,00 

477,660 

99.  8 

22 

100,666 

99.7 

23 

85,000 

28 

29 

13,680,606 

51,000 

30 

14,580 

9S.5 

1910. 

July    11 

6,500.000 

93.6 

12 

1,660,000 

25,000 

u 

14 

4,70 

99.3 

15 

10,  (H 1 

99.7 

20 

5,350,000 

99.6 

Sept.  19 

2,525,000 

30,000 

98.8 

OBJECTIONS   TO   HIGH   TEMPERATURES    FOB    PASTEURIZATION. 


23 


Similar  determinations  were  made  by  Miss  A.  C.  Evans  upon  milk 
pasteurized  in  the  continuous  "Hash"  machine  in  1910.     They  are 

shown  in  Tabic4  9: 

Table  9. — Bacterial  content  of  milk  before  and  after  pasteurization  in  the  continuous 

'  'flash' '  machine  at  160°  F. 


Number  of  bacteria  per  cubic 

centimeter. 

Date. 

Killed  by 
pasteuriza- 

Raw milk. 

Pasteurized 
milk. 

tion. 

1910. 

Per  cent. 

Aug.     3 

7,950,000 

4,700 

99.95 

4 

4,  250, 000 

15,300 

99.65 

5 

9,750,000 

142,000 

98.45 

9 

1,500,000 

4,850 

99.68 

11 

6,450,000 

11,250 

99.83 

15 

2,850,000 

43,600 

98.47 

16 

1,017,500 

12, 725 

98.75 

17 

38,000,000 

700 

99.99 

18 

4,500,000 

6,000 

99.87 

19 

3,750,000 

5,500 

99.86 

24 

18,150,000 

13,800 

99.93 

25 

14,000,000 

6,500 

99.96 

30 

47,300,000 

16,200 

99.97 

Sept.    1 

2, 150, 000 

12,000 

99.44 

7 

5,650,000 

27,000 

99.53 

8 

8,800,000 

63,000 

99.29 

9 

2,800,000 

5,500 

99.80 

12 

10,200,000 

21,200 

99.73 

13 

2,120,000 

18, 500 

99.13 

16 

18,000,000 

5,700 

99.97 

19 

2,525,000 

4,300 

99.83 

21 

1,700,000 

11,000 

99.35 

23 

9,000,000 

30,000 

99.67 

26 

11,200,000 

28,000 

99.75 

OBJECTIONS     TO     HIGHER     TEMPERATURES     THAN 

PASTEURIZATION. 


160°-165°     F.      FOR 


Cheese  made  by  the  new  process  from  milk  pasteurized  at  160°  has 
always  a  clean,  mild  flavor  which  suits  practically  all  markets,  and 
will  please  any  consumer  who  likes  a  mild-flavored  cheese.  Those 
who  are  accustomed  to  and  prefer  very  old  high-flavored  cheese 
would  not  be  suited,  but  estimates  by  leading  cheese  dealers  indicate 
that  the  proportion  of  consumers  preferring  the  high-flavored  cheese 
is  very  small.  Most  of  the  cheese  sold  to-day  is  only  a  few  weeks 
old,  because  the  dealers  generally  avoid  long  storage,  preferring  quick 
sales  and  immediate  profits.  Tins  makes  it  practically  impossible 
for  most  consumers  to  develop  a  taste  for  any  but  the  new  mild 
cheese  sold  in  most  markets.  The  steady  sales  of  pasteurized-milk 
cheese  during  the  past  two  years  indicate  that  the  flavor  of  the  160° 
pasteurized  product  is  satisfactory  for  filling  regular  orders.  Indeed, 
it  is  an  open  question  whether  most  of  the  "high  snappy''  flavor 
often  observed  in  old  cheese  is  not  due  to  the  long-continued,  slow 
development  of  those  same  taints  and  off  flavors  from  unclean  milk 
which  we  recognize  as  objectionable  when  they  develop  rapidly. 


24 


CHEDDAR    CHEESE    I  BOM     PAS!  EUBIZED    MII.K. 


The  use  of  1 1 i lt  1 1 < * i  temperatures  than  160°  For  pasteurization  was 
tried  on  Beveral  days,  with  the  result  that  the  flavor  production  in 
the  cheei  practically  prevented  and  the  texture  was  inferior. 

The  scores  given  to  these  cheeses  are  tabulated  below: 

'Jaii.i    in     Quality  from   milk  pasteurized  ni  different  temperaturet  in  Ou. 

continuous-disk  nun  ■ 


•1  ;it 

Paste  rized  at 

lui     | 

17(1°  F. 

WW  i 

made 

Flavor. 

Ocl     12 

4«i 

- 

27 

18 

13 

40 

28 

35 

IS 

n 

40 

Zl 

IS 

The  scoring  was  done  by  Mr.  F.  W.  Laabs.     The  w>°  cheeses  have 

<  heddar  flavor,  but   taste  like  first-class  cottage  cheese.     They 

jo  crumbly  and  short  that  it  la  impossible  to  draw  a  solid  plug. 

Tlie\   keep  well,  and  it  is  possible  thai  a  good  trade  ought  be  built 

by  the  sale  of  this  product  under  some  such  name  as  "  pressed  cottage 

cheese."     En  all  cases  the  i  se  of  100°  for  pasteurizing  milk  gave  better 

se  than  higher  temperatures. 

Three  reasons  have  been  suggested  why  the  milk  pasteurized  at 

lso°  gives  flavorless  cheese; 

First.    If   bacteria   are   the  essentia]   cause   of   flavor   production,   it 
would   appear  likely   that    the  necessary    kind-   of   milk   bacteria   are 
oyed  by  the  high  temperature  of  pasteurization. 
ond.   If  milk  enzyms  such  as  galactose  are  the  essential  cause 
of  flavor  production,  these  enzyms  are  perhaps  destroyed  by  tie 
of  180°. 

Third.   It  may  be  that  the  casein  or  other  native  milk  constituent 
which  in  normal  cheese  undergo  -  cl  forming  the  flavor-giving 

Bubstances  present  in  ripened  cheese,  is  changed  chemically  either  in 
:  osition  or  as  to  constitution  by  the  heating  to  1J  hat  upon 

cleavage  by  bact<  ria,  enzj  s,  acids,  or  other  agencies  it  yields  differ- 
ent cleavage  product-.  Lacking  the  flavor,  etc.,  which  characterize 
rial  chees 
In  attempting  to  test  the  first  of  these  possible  explanations  a 
variety  of  substances  have  been  added  as  Btarters  to  milk  after 
teurizing  at  180  or  other  high  temperatures  in  order  if  possible  to 
Bupply  the  bacteria  or  enzym  needed  for  normal  curing  and  flavor 
production.  Among  the  special  Btarters  bo  used  were  pure  cultures 
Of  various  bacteria:   raw   milk  up  l()  -(!  P,T  ((',:t  °f  tr,<    V:lt  contents; 

cultures  of  bacteria  isolated  from  jnilk  and  che<  ><  capable  of  develop- 


EFFECT   OF    PASTEURIZATION    ON    (   IIKKSE   CURD. 


25 


ing  1  .(>  percent  or  more  lactic  acid  in  milk  (described  by  Hastings1); 
cheese  of  various  ages  rubbed  to  creamy  consistency  with  milk  and 
added  in  different  proportions  through  a  hair  sieve  to  the  pasteurized 

milk  in  the  vat;  eultures  made  by  adding  cheese  in  this  manner  to 
milk  and  incubating  overnight  before  adding  to  the  cheese  vat.  All 
of  ties-  materials  were  added  to  milk  which  had  been  pasteurized  at 
higli  temperatures  up  to  180°,  and  cheese  was  made  therefrom;  but 
in  no  case  was  it  possible  to  get  a  normal  flavor  development  in  the 
resulting  cheese. 

The  lack  of  flavor  production  under  these  circumstances,  wdiere 
many  kinds  of  bacteria  and  starters  were  added  to  the  pasteurized 
milk,  seems  to  indicate  that  the  casein,  etc.,  in  milk  thus  treated  is 
incapable  of  cleavage  into  the  flavor-giving  substances;  in  other 
words,  that  the  casein,  etc.,  is  changed  chemically  by  the  heat  of  pas- 
teurization.    There  is  additional  evidence  that  such  a  change  occurs. 

EFFECT    OF    PASTEURIZATION    OX    THE    PROPERTIES    OF    CHEESE    CURD. 

A  series  of  cheese  curds  made  from  milk  pasteurized  at  160°,  170°, 
180°,  or  higher  temperatures  show  a  regular  gradation  of  certain  char- 
acteristics. The  higher  the  temperature  of  pasteurization  the  more 
tenaciously  the  curd  retains  moisture  and  the  more  difficult  it  is  to 
expel  the  whey  by  ordinary  means.  This  is  shown  in  the  following 
experiment:  The  milk  in  the  receiving  vat  each  morning  wras  thor- 
oughly mixed  and  then  divided  into  three  portions  which  were  run 
through  the  pasteurizer  at  different  temperatures  and  made  up  into 
cheese  in  different  vats.  Three-fourths  per  cent  of  starter  was  added 
to  each  vat  and  the  milk  and  curds  wrere  handled  in  all  respects  as 
nearly  alike  as  possible,  the  only  difference  being  in  the  temperature 
of  pasteurization.  The  curds  in  separate  hoops  were  pressed  in  the 
same  press,  and  the  next  morning  moisture  tests  were  made  on  each. 
This  entire  work  was  repeated  on  several  days.  The  results  are 
shown  in  Table  11. 

Table  11. — Moisture  content  of  green  cheese  made  from  milk  pasteurized  at  different  tem- 
peratures in  the  continuous-disk  pasteurizer . 


Date. 

Milk  pasteurized  at— 

160°  F. 

170°  F. 

180°  F. 

1909. 
Oct.    12 
13 
14 

Per  cent. 
38.4 
37.0 
39.0 

Per  cent. 
42.2 
39.9 
40.7 

Per  cent. 
46.6 
43.5 
45.5 

i  Hastings,  E.  G.,  Hammer,  B.  W.,  and  Hoffman,  C.    Studies  on  the  bacterial  and  leucocyte  content  ot 
milk.    Wisconsin  Agricultural  Experiment  Station,  Research  Bulletin  6.    Madison,  June,  1909. 


CHEDDAR    CHEESE    FROM    PASTEURIZED    MILK. 


Bach  per  cent  given  is  the  average  of  two  closely  agreeing  dupli- 
cates.    It  i-  seen  that  in  every  case  the  higher  temperatures  of  pas- 
teurization cause  higher  moisture  content  in  tJir  green  cheese.     These 
curds  were  all  cut  with  a  three-eighths-inch  knife  and  heated  to  mi 
in  the  \\  hey. 

Even  when  a  180  curd  w;i>  cut  wit  ]  i  one-fourth  inch  curd  knives 
and  a  KK»  curd  with  three-eighths  inch  knives,  the  moisture  content 
in  the  former  remained  higher,  a--  is  shown  in  the  follow  ing  experiment : 


Taui  k  i_  content  qfcurdi  madefrom  milk  pasteurized  at  different  tunpcratures 

at  the  amt&nuout-disi  pa  U  win  knives  of  different  aizts. 


Milk  pasteurized  at  160°  F. 

Milk  pasteurized  at 

Time     ftftef     cutting 
curd. 

Cut  into 
f-inch 

Cut  into 
|i'ich 

Cat  into 
J-inch 

//.   m. 
1       ()       

Per  cent. 

60.  l 

17  2 

4.}.  a 

42.2 

41.4 

Per  cent. 
70.  0 
63.9 
52.4 
47.2 
45.9 
45.1 

Per  cent. 
66.5 
61.0 
50.6 
#6.0 
44.6 
43.9 

2     o     Drew  whey... 
2    30 

3  30     Milled  curd... 

4  30      Salted  cud... 
4    50      Hooped  curd. 

Each  per  rent  in  the  table  is  the  average  of  two  closely  agreeing 
moisture  determinations. 

It  is  unquestionably  true  that  pasteurized-milk  curds  retain  mois- 
ture more  tenaciously  than  raw-milk  curds,  and  this  effect  is  more 
marked  the  higher  the  temperature  used  in  the  pasteurization.  It 
therefore  follows  that  the  higher  the  temperature  used  in  the  pasteur- 
izer the  greater  will  be  the  weight  of  cheese  obtained  from  pasteurized 
milk.  The  yield  per  hundred  pounds  of  milk  weighed  before  pasteur- 
ization in  each  vat  on  three  days  is  given  in  Table  13. 


Table  13. 


Yield  of  cheese  per  hundred  pounds  of  miU:  pasteurized  at  different  tempera- 
tures. 


Date  made. 

Temperature  of  pasteurizat  ion. 

160°  F. 

170°  F. 

180°  F. 

1909. 
Oct     12 

a 

14 

Poumh. 
12  X 
12.  10 
11.93 

Pounds. 

1.5.42 
1.-  '.'7 

Pounds. 
15.  42 

14.53 
14.44 

It  will  be  shown  later  that  the  yield  of  cheese  obtained  by  pastcur- 
izing  at  lfii i  i>  slightly  greater  than  that  obtained  from  raw  milk,  so 
that  in  this  ropect  the  effect  of  pasteurization  is  distinctly  noticeable 
even  when  the  lower  teniperat ure  is  used  in  the  pasteurizer.     Again, 


EFFECT  OF  PASTEURIZATION    ON    CHEESE   CURD.  27 

among  the  peculiarities  of  pasteurized-milk  curds  is  their  decreased 
power  to  coalesce  or  mat  when  on  the  rack  or  in  the  press.  This 
effect  is  not  noticeable  with  milk  pasteurized  at  160°  to  165°,  but  is 
perceptible  at  170°  and  is  very  marked  when  the  milk  was  pasteurized 
at  180°  or  higher.  The  180°  curd  cubes  when  piled  on  the  rack  pack 
together  like  raisins  or  figs  in  a  box  but  do  not  coalesce  or  unite,  and 
by  rubbing  the  linger  over  the  mass  at  any  time  the  pieces  can  be 
pulled  apart.  The  same  effect  is  noticed  when  the  curd  is  pressed  in 
the  hoop.  The  pieces  pack  together  tightly  but  do  not  unite;  and 
at  any  time  during  the  curing  a  plug  drawn  with  a  trier  will  either 
come  out  in  fragments  or  will  break  into  pieces  instantly  wben  han- 
dled. Instead  of  milling  such  a  curd,  it  is  merely  stirred  or  shaken 
apart  with  the  hands. 

These  two  peculiarities  of  pasteurized-milk  curds,  which  can  not 
be  remedied  or  avoided  by  any  other  means  than  reducing  the  tem- 
perature of  the  pasteurization,  considered  together  with  the  impos- 
sibility of  developing  Cheddar  flavor  after  pasteurization  at  high 
temperatures,  appear  to  indicate  that  the  pasteurization  produces 
some  deep-seated  change  in  the  chemical  constitution  of  casein. 

Another  peculiarity  of  pasteurized  milk,  that  of  coagulating  with 
rennet  only  with  great  difficulty,  need  only  be  mentioned  in  this 
connection,  because  in  the  process  of  cheese  making  here  described 
the  addition  of  hydrochloric  acid  to  the  pasteurized  milk  entirely 
restores  the  coagulability  wTith  rennet,  producing  a  curd  in  many 
respects  superior  to  and  easier  to  handle  than  the  curd  commonly 
obtained  in  the  regular  way  from  raw  milk. 

From  what  has  been  said  it  will  be  seen  that  the  use  of  160°  to  165° 
for  pasteurization  offers  many  practical  advantages.  It  is  sufficiently 
high  to  check  effectually  the  further  ripening  of  the  milk  during  the 
next  few  hours,  while  the  use  of  150°  is  not  high  enough  for  this  pur- 
pose. Furthermore,  160°  gives  cheese  of  cleaner  flavor  than  140°  or 
150°  (no  doubt  by  more  effectual  destruction  of  taint-producing 
bacteria)  or  than  raw  milk,  as  shown  in  Table  6.  It  may  be  mentioned 
also  that  over  99  per  cent  of  the  total  bacterial  content  of  the  milk  is 
destroyed  by  use  of  160°,  as  shown  in  Tables  8  and  9.  The  160°  is 
preferred  to  170°  or  180°  because  the  cheese  obtained  by  the  use  of 
160°  is  more  nearly  like  the  best  American  cheese  in  moisture  content 
(see  Table  11)  and  in  texture  and  flavor.      (See  Table  10.) 

So  far  as  it  is  possible  to  say  at  the  present  time,  the  use  of  160°  is 
sufficient  to  kill  most  probably  99  per  cent  of  the  gas  and  taint- 
forming  bacteria  in  milk.  It  can  not  be  claimed  that  they  are  all 
killed,  because  it  is  true  that  when  very  unclean  milk  is  handled  by 
this  process  the  cheese  sometimes  shows  slight  traces  of  unclean 
flavors,  though  not  enough  to  affect  the  market  value.  While  gas 
and  pin  holes  have  often  been  seen  during  the  seasons  of  1909,  1910, 


OHEDDAB   CHEESE    FROM    PASTEURIZED    MILK. 

and  1911  in  cheese  n  ade  l»\  regular  methods  at  this  factory,  no 
whatever  was  Been  in  any  curd  or  cheese  n  ade  during  1909  or  1**1 1 . 
and  the  obtained,  nine  days  in  succession,  in  1910  was 

demons!  rated  to  be  due  to  the  use  by  mistake  of  st  arter  which 

added  to  the  i   ilk  after  pasteurization.    The  fault  arose  at  thai 
fro  i  the  ii  efficient  n  i  ai  -  then  at  J. a:  d  for  pre]  aring  and  heat- 
ing milk  for  propa  at  ion  of  i  he  si  arter.    An  in  prov<  d  stea   i  sterilizer 
was  at  once  Bet  up  for  this  purpose,  which  prevented  all  further  diffi- 
culty of  this  soil  during  the  past  two  years. 

The  temperature  finally  selected  as  most  completely  securing  the 
advantages  and   avoiding  the  disadvai  of  pasteurization   for 

cheese  making  is  160    to  165    F.     In  practice  the  pasteurizer  is 
running  at  163    and  held  th<  re  as  closely  as  possible. 

THE    DIFFERENT    TYPES    Oi    CONTINUOUS    PASTEURIZERS    DSED. 

Two  different  pasteurizers  were  used  in  this  work  with  entire 
Buccess,  being  apparently  equally  effective  in  producing  the  des 
results  at  160  to  165  .  Tj  ese  were  a  disk  machine  of  2,000  pounds 
per  J  cur  capacity  and  a  "flash"  n  achine  of  1,200  pounds  capacity 
per  ho  p.  See  Pis.  II  and  111.)  The  choice  between  these  two  types 
of  pasteurizing  machines  for  use  in  this  process  appears  to  depend 
upon  their  relative  cost  and  ease  of  operation  and  cleaning,  rather 
than  upon  any  diff<  rence  in  eff<  cl  iven<  bs.  They  w<  re  us<  d  alternately 
on  successive  day-  for  several  week-,  and  on  three  day-.  September  1 . 
1l\  and  l(.>.  1910,  the  milk  was  divided,  one-half  being  run  through 
each.  The  cheese  was  first  class  in  each  case  and  Bhowed  no  differ- 
ence s  that  ( ould  be  traa  d  to  the  use  oi  different  machini  9. 

THE  ACIDULATION    PROCESS. 
THE    STANDARD    ACDDITl     OF    MILE    FOB    CHEESE    MAKING. 

Milk  as  it  Bows  from  the  pasteurizer  varies  daily  in  acidity  and  is 
Lacking  in  bacteria  of  the  lactic-acid  type,  needed  to  aid  in  cl 
curing.     By  the  addition  of  sufficient  hydrochloric  acid  to  raise  the 

acidity  of  the  milk  to  0.25  per  C4  nt  (as  lactic  acid'  after  pasteurizing, 
and  of  three-fourths  per  cent  of  a  first-class  -tarter,  the  pasteurized 
milk  i-  brought  daily  into  Standard  condition  both  as  to  acidity  and 
bacterial  content  for  cher-e-n  akiiiLT  purposes.  The  reasons  for 
adding  acid  and  -tarter  a-  specific  d  will  row   be  given  in  detail. 

The  Btandard  acidity  is  0.25  per  cent,  and  the  acidity  of  pasteur- 
ized milk  i-  raised  to  this  figure  rather  than  to  0.20  or  0.30  per  cent 

for  the  following  tea-' 

PilBt.    In   regular  cheese  making  the  acidity  of  whey  when  drawn 

b   on  the  average,  about  0.17  per  cent,  corresponding  to  an  acidity 


STANDARD   ACIDITY    OF    MILK.  29 

of  milk  of  about  0.2.">  per  cent.  Anyone  can  test  the  correctness  of 
this  statement  by  transferring  a  pint  of  milk  from  a  cheese  vat,  just 
before  adding  rennet .  to  a  small  tin  pail,  keeping  the  milk  sample  at 
the  same  temperature  as  the  vat  and  titrating  the  milk  in  the  pail  as 

well  as  whey  from  the  vat  at  intervals.  When  the  whey  reaches  0.17 
pei  cent  the  milk  reaches  nearly  0.25  per  cent. 

The  control  of  acidity  at  the  instant  the  whey  is  drawn  is  commonly 
regarded  as  most  important  in  regular  cheese  making.     With  milk 

pasteurized  at  160°  there  is  little  or  no  increase  of  acidity  (usually 
about  0.01  per  cent)  in  whey,  before  the  whey  is  drawn.  The  acidity 
of  milk  is  adjusted  to  0.25  per  cent  in  this  process  after  pasteurizing 
in  order  to  parallel  ordinary  working  conditions  at  the  time  of  drawing 
the  whey. 

Second.  Mixed  milk  in  the  factory  cheese  vat  is  commonly  at  0.16 
to  0.18  per  cent  acidity  when  received,  although  often  at  0.19  to  0.21 
per  cent.  It  should  never  be  over  0.23  per  cent  acidity.  It  is  found 
that  an  addition  of  hydrochloric  acid  equal  to  at  least  0.02  per  cent 
of  lactic  acid  is  required  to  restore  the  coagulability  with  rennet  to 
such  milk  after  pasteurization,  but  the  daily  addition  of  only  0.02 
per  cent  of  acid  would  leave  the  milk  of  varying  acidity,  which  is 
objectionable.  If  0.20  per  cent  were  adopted  as  the  standard  acidity, 
after  adding  0.02  per  cent  in  the  form  of  hydrochloric  acid,  this  rule 
would  exclude  from  use  all  milk  having  a  higher  acidity  than  0.18 
per  cent  when  received,  which  it  is  not  desirable  to  do.  Only  rarely 
is  a  vat  full  of  milk  at  0.23  per  cent  acidity  received  at  any  factory, 
but  even  such  milk  can  be  handled  in  the  routine  manner  at  the  stand- 
ard acidity  of  0.25  per  cent  by  adding  the  required  0.02  per  cent  of 
hydrochloric  acid  after  pasteurization. 

It  might  be  stated  as  a  matter  of  record,  not  as  a  precedent  for 
factory  practice,  that  vats  of  milk  of  0.24  to  0.28  per  cent  acidity 
when  received  have  been  successfully  made  up  into  good  cheese  with- 
out varying  the  process  in  any  particular,  excepting  that  only  enough 
acid  is  added  after  pasteurization  to  raise  the  acidity  0.01  per  cent, 
which  is  sufficient  to  restore  the  rennet  coagulation  to  such  ripe  milk. 
The  only  apparent  limit  of  acidity  for  milk  to  be  handled  by  this 
process  is  that  the  milk  should  not,  of  course,  be  sour  enough  to 
curdle  in  the  pasteurizer,  and  this  limit  is  reached  at  or  about  0.30 
per  cent. 

However,  it  should  be  recognized  by  everyone  that  milk  that  has 
reached  0.30  per  cent  or  even  0.25  per  cent  acidity  before  it  gets  to 
the  cheese  factory  must  have  received  very  poor  care  and  attention 
on  the  farm  and  must  be  entirely  unfit  for  cheese  making  from  a  sani- 
tary point  of  view. 


30  CHEDDAB   CHEESE    PROM    PASTEURIZED    MILK. 

COMPARISON    <>i     DIFFERENT    KINDfl   "I      iCWB    FOB    USE    EN    CHEESE 

M  \  1 1 "  •  ■ 

( )f  the  more  common  acids  sulphuric,  hydrochloric,  and  phos- 
phoric the  first  is  the  least  convenient  to  handle,  especially  in  a 
cheese  factory  .  be<  ause  of  the  great  an  ount  of  heat  liberated  when  it 
is  diluted,  and  the  impossibility  of  diluting  it  in  the  carboy  in  which 
■■  i  ved.  Hydrochloric  acid  is  much  better  in  this  respect 
as  n  <an  be  readily  diluted  with  an  equal  volume  of  water  by  pouring 
the  water  into  the  acid  with  no  danger  and  very  little  heat  evolution. 

Tims  diluted  it  I'm:  <  -  \  cry  lit  t  le.  if  at  all.  and  (  an  be  readily  and  ac<  u- 

ratelj  standardized  by  titration  with  norma]  soda  and  phenol- 

phthalein  indicator.  Phosphoric  acid  can  be  purchased  in  carboys 
of  about  50  per  cent  strength,  requires  no  dilution  in  the  carboy,  and 
Liberates  little  or  no  heat  when  diluted. 

The  choice  between  hydrochloric  acid  and  acid  made  from  phos- 
phorus is  greatly  in  favor  of  the  former  because  of  the  high  cost  of 
the  latter.  Recently,  however,  phosphoric  acid  made  from  bon 
or  hone  black  has  been  put  on  the  mark*  t  in  this  country,  containing 
about  45  per  cent  five  phosphoric  acid  and  less  than  1  per  cent  each 
of  hydrochloric  acid,  sulphuric  acid,  and  phosphates  of  iron  and 
alumina,  this  product  being  offered  at  6  cents  a  pound  in  paraffined 
barrels.  The  price  of  this  acid  is  very  nearly  the  same  as  that  of  chem- 
ically pure  hydrochloric  acid  for  equal  neutralizing  power. 

Chemically  pure  hydrochloric  acid  is  and  has  been  for  years  a  stand- 
ard article  of  manufacture,  whose  purity  is  tested  daily  by  use  in 
hundreds  of  laboratories.  On  the  other  hand,  the  manufacture  oi 
phosphoric  acid  from  bone  ash  in  a  form  free  from  objectionable 
impurities  has  been  accomplished  only  very  recently. 

A  number  of  cheeses  were  made  with  phosphoric  acid,  but  these 
showed  no  advantage  over  those  made  with  hydrochloric  acid ;  indeed 
t  hey  Be  >med  to  have  a  Blight  peculiarity  of  flavor,  as  a  rule,  after  curing. 
Most  of  the  cheeses  made  from  pasteurized  milk  have  bo  far  been  made 
with  hydrochloric  acid,  and  the  use  of  this  acid  is  described  and  rec  o:n- 
mended  in  the  present  bulletin. 

The  selection  of  hydrochloric  a<  id  was  made  because  it  is  cheap 
and  more  easily  obtained  than  any  other  chemically  pure  acid,  and 
being  a  natural  i  onstituent  of  gastric  juice  in  the  human  stomach,  no 
objr<  tion  could  be  raised  on  sanitary  or  other  grounds  against  its  use 
m  this  p 

TIIK    PROPORTION    OF    HYDROCHLORIC     \(  ll>    REQUIRED    DAILY. 

it  is  necessary  to  determine  first  what  the  acidity  of  each  vat  of 

the  mixed  milk  is.  in  order  after  pasteurizing  to  add  the  requisite 
quantity  of  hydrochloric  acid  to  bring  the  acidity  up  to  0.25  per  cent. 
Where  only  one  vat  of  milk  i^  to  be  pasteurized  and  only  one  workman 


TESTING    MILK    FOR   ACIDITY.  31 

is  employed  it  is  probably  better  to  weigh  in  all  the  milk  then  stir  the 
vat  well  and  take  out  a  half  cupful  of  milk  for  the  acid  test. 

Where  two  men  are  employed  and  it  is  desired  to  start  the 
pasteurizer  running  as  early  as  possible  (before  the  receiving  vat  is 
full),  the  intake  man  should  take  from  each  weigh  can  of  milk  a 
sampling  tube  full,  mixing  these  samples  in  a  pint  jar.  The  acidity  of 
this  mixed  sample  will  then  be  the  same  as  the  average  acidity  of  all 
the  milk  run  into  the  vat.  As  soon  as  one  vat  full  of  milk  (say  5,000 
pounds)  has  been  run  from  the  weigh  can  into  the  receiving  vat,  the 
pint  jar  containing  the  sample  for  the  acid  test  is  handed  from  the 
intake  to  the  man  running  the  pasteurizer,  together  with  the  total 
weight  of  milk  run  into  that  vat.  The  pasteurizer  was  started  when 
perhaps  only  half  of  this  milk  had  been  received,  but  the  receiving 
vat  is  still  about  half  full,  and  after  making  the  acid  test  on  the  sample 
the  operator  can  tell  exactly  how  much  more  hydrochloric  acid  must 
be  added,  while  pasteurizing  the  remaining  milk  in  order  to  bring  the 
acidity  of  the  whole  vat  up  to  the  right  point,  or  0.25  per  cent. 

TESTING   MILK   FOR   ACIDITY. 

In  determining  the  acidity  of  milk,  measure  a  17.6  cubic  centimeter 
pipette  full  of  milk  sample  into  a  white  china  cup,  which  should  be 
shallow  and  wide  rather  than  narrow  and  deep.  Add  two  drops  of 
phenolphthalein  indicator  and  while  shaking  or  stirring  the  milk  in 
the  cup  run  in  tenth-normal  alkali  (Manns's  solution)  from  a  burette, 
rapidly  at  first,  and  later  by  single  drops,  until  the  faint  pink  color  pro- 
duced by  the  last  drop  does  not  disappear  on  thorough, mixing.  The 
volume  of  tenth-normal  alkali  used  is  read  from  the  burette,  and  this 
volume  divided  by  20,  which  can  be  done  mentally,  gives  the  exact 
acidity  of  the  milk  in  per  cent  of  lactic  acid  by  weight.  For  example, 
if  the  volume  of  alkali  solution  used  was  3.2  cubic  centimeters  the 
acidity  is  3.2  divided  by  20,  which  equals  0.16  per  cent.  Subtracting 
the  acidity  of  the  raw  milk  from  0.25  per  cent  shows  how  much  the 
acidity  of  the  milk  is  to  be  raised  with  hydrochloric  acid  after  pas- 
teurizing. For  example  subtracting  0.16  per  cent  from  0.25  per  cent 
leaves  0.09  per  cent,  which  shows  that  the  acidity  is  to  be  increased 
0.09  per  cent  with  hydrochloric  acid. 

The  outfit  needed  for  testing  milk  is  shown  in  Plate  I.    It  consists  of: 

1.  A  burette  with  rubber  tip  and  pinchcock;  capacity  25  c.  c,  with 
Yo  c.  c.  graduations. 

2.  A  17.6  c.  c.  pipette  as  used  for  the  Babcock  test. 

3.  A  white  china  teacup,  which  is  best  if  shallow  and  wide  and  with 
flat  bottom. 

4.  A  support  for  the  burette,  which  may  be  an  iron  stand  and  clamp, 
or  a  wooden  strip  with  a  hole  in  it,  fastened  to  a  window  casing,  as 
shown  at  the  left  in  Plate  I. 


CHEDDAB   CHB]  4    PASTEUBIZBD    MII.K. 

\  rubber-stoppered  bottle  of  Manns's  -  luti  d  (tenth-normal 
alkali  which  may  be  purchased  at  SI  per  gallon  of  dealers  in  dairy 
supplies,  or  may  be  made  by  diluting  the  normal  alkali  b  Lution, 
which  mu>t  be  purchased  as  it  is  required  in  this  pr  i  ess  as  described 
on  i' 

ii     \  2-ounce  or  t-ounce  bottle  of  phen  lphthalein  indicat  r  b  -lu- 
ti .n. 

7.  The  additional  outfit  required  for  use  in  this  pr  cesa  of  clu 
making  is  ale  i  shown  in  the  figure.  It  coi  sists  of  1  gallon  of  normal 
alkali  (ten  times  as  Btrong  as  Manns's  neutralizer  .  a  50  cubic  centi- 
meter measuring  flask,  a  500  cubic  centimeter  measuring  cylinder,  and 
a  2  cubic  centimeter  pipette,  which  should  be  accurately  made.  A 
gallon  of  n  rmal  caustic  alkali  contains  about  5  ounce-  of  ca 

s  mIji.  Worth  about   15  cent-,  and  Bh  »ul<l  C    Bt  the  cheese  maker  IK » more 

than  a  gall  »n  of  tenth-normal  -  luti  n     that  is,  ab  lit  $1. 

PRESERVING    THE    TENTH-NOEMAL    SOLUTION. 

[nstead  of  using  the  large  b  »ttle  of  tenth-m  rmal  a  luti  -n  t  i  fill  the 
burette  with,  it  is  mucb  better  t  •  get  a  -mailer  b  .ttle,  holding  6  or 
8  ounce-,  al-  i  pr  >\i  lei  with  a  rubber  -t  >pper,  and  to  fill  this 
smaller  b  ttle  occasi  'Dally  fr  m  the  Larger  b  ttle.  which  is  then  put 
away,  tightly  Bt  >ppered,  in  a  Bafe  place.  The  small  1>  ttle  is  kept 
near  the  burette  and  used  daily  in  filli  ig  it.  and  the  large  b  ttle  is 
thus  pr  tected  from  unnecessary  exp  sure.  1  ss  <  f  strength,  and  fr  >m 
r  \  Bpilling.  The  use  I  f  tw  i  h  .ttles  in  this  manner  has  pr  vcn 
in  si  satisfactory  in  this  lal><  ratory  and  dairy  school  during  the  past 
four  year-.  It  i-  recommended1  as  a  means  of  avoiding  less  of 
gth  thr,  ugh  exp'  -ere  to  the  air.  which  has  bereft  f*  re  been  the 
greatest  difficulty  to  overct  me  in  the  i  Be  of  Manns's  test  in  the  cl 

factory. 

DILUTING    NORMAL    ALKALI    TO   TENTH-NORMAL. 

One  may  prepare  tenth-normal  alkali  by  diluting  the  normal  alkali 
11  avs:  Tour  into  a  500  cubic  centimeter  graduated  cylinder 
exactly  "><>  cubic  centimeter-  of  the  normal  s  lution  measured  in  the 
on  cubic  centimeter  Bask.  Add  at  once  150  cubic  centimeters  of  pure 
water,  either  rain  water  or  condensed  -team.  Pour  the  mixture  into 
a  (lean  Lrla--  bottle,  mix  by  shaking,  and  keep  stoppered  with  a 
rubber  stopper  to  avoid  loss  i  f  strength  by  exp:  sure  to  air.  If  the 
mixture  is  muddy  or  turhi  1.  the  water  used  in  diluting  was  not  pure. 
A  Blight  turbidity  may  he  neglected. 

o.J  I.  I  !,-•  pit  .'\;ition  of  Mann's  alkaline  solution  in  cheese  factories.  Hoard's  Dairyman, 
vol.  41),  No.  41,  p.  1200.     Fort  Atkinson.  Wis.,  Nov.  12,  1909. 


U.  S.  Dept.  of  Agriculture. 


Plate  I. 


z  z 

<  * 

—  < 

m  * 

t-  05 

Q  uj 

O  I 

<o 

z 

z  a 

<  HI 


b  o 
a  < 

o 

< 


I  Id,    U.    S.    [j  •'•     "  (  ULTURF. 


Plate  II. 


Bul.  165,  Bureau  of  Ammal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  III. 


ADDITION   OF   ACID   TO    MILK.  33 

ADDING    ACID   TO    MILK    AFTER    PASTEURIZATION. 

For  (his  purpose  the  acid  of  normal  Btrength  is  placed  in  an  acid- 
proof  container  on  a  shelf  near  the  outlel  of  the  cooler.  A  glass  bottle 
or  a  paraffined  wooden  cask  can  be  used,  as  shown  in  Plate  III.  The 
container  has  a  small  opening  on  one  side  near  the  bottom,  through 
which  the  acid  is  drawn  by  a  rubber  tube  of  one-eighth  or  one-quarter 
inch  internal  diameter  closed  by  a  screw  pinchcock.  On  the  outside 
wall  of  the  container,  beginning  at  the  top,  a  scale  is  engraved  or 
otherwise  permanently  attached,  with  graduations  showing  pounds, 
halves,  and  quarters  of  acid  delivered.  If  the  container  is  opaque,  a 
iz-lass  level-tube  placed  outside  near  the  scale  shows  the  acid  level 
within  at  any  time.  The  capacity  of  the  acid  container  should  be 
about  10  gallons  for  use  with  a  7,000-pound  vat  of  milk.  In  addition, 
a  two-quart  tin  pan  is  connected  by  means  of  a  short  piece  of  con- 
ductor to  the  cooler  outlet.  The  milk  from  the  cooler  and  acid  from 
the  container  are  thoroughly  mixed  in  the  conductor  and  mixing 
pan,  from  which  the  acidulated  milk  overflows  and  runs  into  the 
cheese  vat. 

In  order  to  avoid  coagulation  of  milk  with  acid,  the  acid  is  added 
from  a  jet  so  as  to  strike  the  cooled  milk  while  the  latter  in  a  thin 
stream  is  moving  rapidly  down  the  short,  steeply  inclined  piece  of 
open-conductor  pipe.  The  mixture  then  enters  the  mixing  pan  and 
its  direction  is  abruptly  changed  twice,  thus  securing  thorough 
mixing  of  milk  and  acid  before  it  flows  over  the  edge  of  the  pan  into 
the  cheese  vat. 

In  using  this  acidulator  there  is  never  any  danger  of  coagulation  if 
the  operator  remembers  always  to  shut  off  the  acid  before  the  milk 
flow  stops.  It  has  been  repeatedly  shown  that  2  pounds  of  acid, 
or  twice  as  much  as  commonly  required,  can  be  safely  added  in  this 
manner  to  100  pounds  of  milk  at  60°  to  80°  F.  without  causing  coagula- 
tion. If  any  small  particles  of  curd  are  formed,  they  rise  to  the 
surface  of  the  milk  when  quiet  in  the  vat  and  can  be  plainly  seen. 
They  can  then  be  taken  up  with  a  hair  sieve  and  rubbed  through  the 
sieve  into  the  milk  without  causing  loss  of  yield.  In  practice,,  the 
acidity  of  the  vat  of  milk,  when  all  in  and  stirred,  always  comes 
between  0.24  and  0.26  when  attempting  to  make  it  0.25  per  cent, 
and  this  degree  of  accuracy  is  entirely  satisfactory. 

CALCULATING   THE    AMOUNT    OF    ACID    TO    BE    ADDED. 

To  calculate  how  many  pounds  of  normal  hydrochloric  acid  are 
required  by  any  vat  of  milk  after  pasteurizing,  it  should  be  remem- 
bered that  1  pound  of  the  acid  added  to  100  pounds  of  milk  will  raise 
its  acidity  just  nine  hundredths  (0.09)  per  cent.     From  this  it  is  easy 
79994°— Bull.  165—13 3 


:;l 


CHEDDAR    <   HEESE    FROM     PASTEURIZED    MILK. 


Be  thai  for  2,500  pounds  of  milk,  of  0.16  per  cent  acidity,  just  25 
pounds  of  normal  strength  acid  will  be  required,  and  for  3,050  pounds 
..f  milk  30.5  pounds  of  acid  will  l>c  needed,  etc.  If  the  milk  Bhowed 
an  acidity  of  0.21  per  cent  when  raw,  then  subtract  0.21  from  0.25, 
which  Leaves  0.04  percent.  In  this  case,  since  the  milk  is  riper  to 
atari  with,  less  acid  will  need  to  be  added;  only  four-ninths  of  a  pound 
id  for  each  100  pounds  of  milk  will  be  accessary  to  bring  the  acid- 
ity up  from  0.21  to  0.25  per  cent.     In  any  case  the  weight  in  pounds 

..              ,.           ..    0.25     acidity  of  raw  milk     weight  of  milk. 
«•!  acid  required  is  equal  to =^ X —     «^ — 


.09  'x  LOO 

•  ,.       r            .„      weight  of  milk  ,  .  , 

or  0.25     acidity  of  raw  milk  x-        Q  n Stated  in  words  the 

rule  is,  divide  the  weight  of  milk  by  9  and  multiply  by  0.25  minus 

the  acidity  of  the  raw  milk. 

The  following  table  shows  the  amount,  in  pounds,  <>f  normal  acid 
required  to  be  added  for  each  loo  pounds  of  milk  when  the  acidity 
of  the  latter  before  pasteurizing  is  0.15,  and  for  each  one-hundredth 
increase  up  to  0.27: 

Table  14. —  Weight  of  normal  acid  required  to  be  added/or  each  100  pounds  of  milk. 


Weight  of 

Acidity  of 

normal 

Aciditv  of 

milk  when 

arid  added 

milk  nfter 

pasteur- 

to 1(H) 

the  addi- 

ized. 

jKMinds  of 
milk. 

tion  of  acid. 

Per  cent. 

Pounds. 

Per  cent. 

o.  us 

1.11 

0.25 

.16 

1.00 

.25 

.17 

n 

.25 

.18 

:: 

.25 

.19 

.66 

.25 

.20 

.55 

.25 

.21 

.44 

.25 

.2l> 

.  83 

.25 

.22 

.25 

.24 

.11 

.25 

.11 

.  38 

.11 

.27 

.11 

Where  milk  appears  to  be  of,  say.  ( ) . 1 7 ">  per  cent  acidity  when 
n •<  i  ived,  it  is  treated  as  if  it  were  at  0.17  percent,  dropping  the  0.005 
out  of  the  calculation. 

The  following  table,  conveniently  posted,  may  aid  in  calculating 

the  weight  of  acid  required  for  any  weight  of  milk  at  any  acidity: 


PREPARATION    OF    NORMAL    HYDROCHLORIC    ACID. 


35 


Table  L5.     Weight  of  normal  hydrochloric  acid  required  for  stated  quantities  oj  milk  at 

stated  aridities. 


Hydrochloric  acid  required  when  acidity  is 

Weteht 

of  milk. 

0.27  tO 
0.24. 

0.23. 

0.22. 

051. 

0.20. 

0.19. 

0.1S. 

0.17. 

0.16. 

0.16. 

0.14. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

10,  (XX) 

ll.l 

33.  3 

44.4 

55.5 

till,  (i 

77.7 

Ss.  s 

100.0 

111.  1 

L22.0 

9,000 

10.0 

20.0 

30.0 

40.0 

50.0 

60.0 

70.0 

80.0 

90.0 

1(H).  1) 

L10.0 

8,000 

8.9 

17.8 

26.7 

35.6 

44.4 

53.3 

62.2 

71.1 

80.0 

88.  9 

97.8 

7,000 

7.8 

15.5 

23.3 

31.1 

3S.9 

46.7 

54.4 

62.2 

70.0 

77.8 

85.  6 

6,000 

6.7 

13.3 

20.0 

26.7 

33.3 

40.0 

46.7 

53.3 

60.0 

66.7 

73.3 

5,000 

5.6 

11.1 

16.7 

22.2 

27.8 

33.3 

38.9 

44.4 

50.0 

55.  5 

61.1 

4,000 

4.4 

8.9 

13.3 

17.8 

22.2 

26.7 

31.1 

35.5 

40.0 

44.4 

48.9 

3,000 

3.3 

6.7 

10.0 

13.3 

16.7 

20.0 

23.3 

26.6 

30.0 

33.3 

36.7 

2,000 

2.2 

4.4 

6.7 

8.9 

11.0 

13.3 

15.6 

17.8 

20.0 

22.2 

24.4 

1,000 

1.1 

2.2 

3.3 

4.4 

5.5 

6.7 

7.8 

8.9 

10.0 

11.1 

12.2 

IKK) 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

8.0 

9.0 

10.0 

11.0 

800 

.9 

1.8 

2.7 

3.6 

4.4 

5.3 

6.2 

7.1 

8.0 

8.9 

9.8 

700 

.8 

1.6 

2.3 

3.1 

3.9 

4.7 

5.4 

6.2 

7.0 

7.8 

8.6 

600 

.7 

1.3 

2.0 

2.7 

3.3 

4.0 

4.7 

5.3 

6.0 

6.7 

7.3 

500 

.6 

1.1 

1.7 

2.2 

2.8 

3.3 

3.9 

4.4 

5.0 

5.6 

6.1 

400 

.5 

.9 

1.3 

1.8 

2.2 

2.7 

3.1 

3.6 

4.0 

4.4 

4.9 

300 

.4 

.7 

1.0 

1.3 

1.7 

2.0 

2.3 

2.7 

3.0 

3.3 

3.7 

200 

.2 

.4 

.7 

.9 

1.1 

1.3 

1.6 

1.8 

2.0 

2.2 

2.4 

100 

.1 

.2 

.3 

.4 

.6 

.7 

.8 

.9 

1.0 

1.1 

1.2 

75 

.08 

.17 

.25 

.34 

.42 

.50 

.60 

.67 

.75 

.83 

.92 

50 

.06 

.11 

.17 

.22 

.28 

.33 

.39 

.44 

.50 

.56 

.61 

25 

.03 

.06 

.09 

.11 

.14 

.16 

.19 

.22 

.25 

.28 

.31 

To  find  how  much  normal  hydrochloric  acid  will  be  needed  to 
raise  6,754  pounds,  for  example,  of  milk  of  0.17  per  cent  acidity  to 
0.25  per  cent  acidity,  take  from  the  table  the  figure  given  under  0.17, 
opposite  6,000,  which  is  53.3;  add  to  this  the  figure  opposite  700, 
which  is  6.2;  then  add  the  figure  opposite  50,  which  is  0.44;  the  total 
gives  the  number  of  pounds  of  acid  required,  namely,  59.9  pounds. 

PREPARATION  OF    NORMAL    HYDROCHLORIC    ACID    IN    THE    CHEESE 

FACTORY. 

Chemically  pure  hydrochloric-acid  solution,  as  purchased  in  carboys 
containing  about  120  pounds  each,  contains  about  40  per  cent  by 
weight  of  hydrochloric  acid  and  60  per  cent  of  water,  and  costs  about 
7  cents  a  pound.  Its  strength  varies  somewhat,  and  it  must  be 
diluted  with  water  before  it  can  be  added  to  milk  in  this  process. 
The  preparation  of  normal-strength  acid  used  in  cheesemaking  is 
carried  on  at  the  cheese  factory  in  two  steps,  as  follows: 

First  step. — Kemove  the  wooden  cap  from  the  top  of  a  fresh  carboy 
of  acid  and  loosen  the  glass  plug  in  the  neck  by  tapping  it  on  different 
sides  very  gently  with  a  piece  of  wood  (not  metal)  until  it  can  be 
drawn  out  readily  with  the  hand.  Set  an  empty  carboy  alongside  the 
newly  opened  carboy.  Fill  both  limbs  of  a  glass  siphon  with  water, 
removing  all  air  bubbles,  and  insert  the  two  limbs  into  the  carboys  at 
once,  as  shown  in  Plate  IV.  When  the  siphon  is  in  place,  as  shown  in 
the  lower  figure,  the  acid  will  flow  from  the  full  carboy  into  the  other 
until  in  about  half  an  hour  each  is  practically  half  full.     Xow  fill  up 


OHEDDAB   (  ill.!. si:    I  BOM    PAS1  BUBIZBD   MIl.K. 

each  carboy  nearly  to  the  neck  with  water.  Leaving  -pace  enough 
beneath  the  neck  to  permit  mixing  the  contents  readily  by  Bhaking. 
Tip  each  carboy  up  on  one  edge  and  rock  vigorously  for  about  five 
minutes  with  the  stopper  out  to  induce  thorough  mixing.     The  liquid 

gets  Blightly  wanner  <»n  mixing,  and  il  18  stoppered  and  Jei'l  to  -land 
OVemighl    tO  COOl   and   i-   then   called   "•dilute*'   acid. 

To  determine  how  much  further  each  carboy  of  dilute  acid  requires 
to  be  diluted  with  water  to  make  it  exactly  "normal"  iii  strength,  set 
up  the  burette  used  in  Mann-'-  test,  but  fill  it  with  normal  alkali  solu- 
tion, which  is  10  times  as  Btrong  as  that  used  in  testing  milk.  I 
a  _'  cubic  centimeter  pipette,  transfer  exactly  2  cubic  centimete 
the  dilute  acid  from  the  carboy  to  the  porcelain  cup  containing  a  Little 
pure  water,  letting  the  pipette  drain  into  the  cup  half  a  minute  by  the 

watch  and  blowing  OUt  the  la-t  drop  of  acid  from  the  tip  into  the  cup. 

Now  add  one  or  two  drops  of  indicator  and  after  reading  the  Level  of 
alkali  in  the  burette,  draw  out  the  alkali  from  the  burette,  precisely  as 
in  testing  milk,  rapidly  at  first,  Later  by  single  drops  while  Bhaking 

the  cup  in  a  circle  until  the  last  drop  added  produces  a  distinctly  pink 
color  which  remains  throughout  the  entire  Liquid  after  thorough  mix- 
ing. Read  and  record  the  volume  of  alkali  solution  used.  Kinse  out 
the  cup,  lill  up  the  burette,  shake  up  the  acid  in  the  carboy  for  a 
minute  and  test  another  2  cubic  centimeters  of  the  acid  for  the  sake 
of  accuracy. 

If  the  contents  of  the  carboy  were  thoroughly  mixed  at   first,  the 

two  titrations  will  agree  closely,  not  differing  by  more  than  0.20  cubic 
centimeter.  If  they  do  not  agree,  the  carboy  contents  were  probably 
not  well  mixed  at  first,  and  should  be  given  another  very  thorough 
Bhaking  for  five  minutes,  after  which  the  titration-  are  repeated. 
Once  thoroughly  mixed  the  acid  and  water  remain  mixed,  and  never 
need  in  be  shaken  again. 

Suppose  that  in  the  two  tests  the  2  cubic  centimeters  of  acid 
required  11  and  11.2  cubic  centimeters  of  normal  alkali  to  produce 
the  pink  color,  the  average  being  11.1  cubic  centimeters.  Divide  the 
volume  of  alkali  by  2     the  volume  of  acid  used-— which  gives  in  this 

_J_ «  5.55.      Tin-   means  that    the  acid   i-  5.55  time-  as  Btrong 

a-  it  should  be  for  normal  acid,  and  that  it  must  be  diluted  to 
tune-  it-  volume  with  water  to  make  it   exactly  normal  in  strength. 
The   work   described    above    i-   performed   once   on   each   carboy   of 
dilute  acid   before   Using  it    for  cheesemaking,   and   the  object    i-  to  get 

the  figun  in  tlii-  case)  which  shows  how  much  too  Btrong  the 

acid  is,  and  how  much  it  mu-t  be  diluted  to  make  it  normal  in 
strength. 

Hi  />.     The  Becond  Btep  consists  in  diluting  up,  each  day,  as 
much  of  the  acid  as  will  be  needed  for  the  milk  on  that   day.      This 


Bul.  165,  Bureau  of  Ammal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  IV. 


FULL  CARBOY  OF 
HYDROCHLORIC  ACID 


EHPTY   CARBOY 


Transferring  Acid  from  Full  to  Empty  Carboy  by  Means  of  Siphon. 


I  thy,  U.  S.  Dept.  of  Agriculture. 


Plate  V. 


DIRECTIONS  FOR  PASTEURIZING  AND  ACIDULATING    All  IK.  37 

is  performed  as  follows:  Having  determined  thai  the  dilute  acid  is 
5.55  times  Btronger  than  normal,  the  acid  is  further  diluted  for  use 
each  day,  adding  1  volume  of  acid  to  4.55  volumes  of  water,  thus 
making  the  total  volume  5.55  times  as  great  as  the  acid  used. 

To  do  this,  measure  out  any  convenient  volume  (say  500  cubic 
centimeters  for  about  2,500  pounds  of  milk)  of  the  acid  in  a  glass 
cylinder  and  add  it  to  4.55  times  its  volume  of  water  (in  this  case 
500x4.55  =  2/275  cubic  centimeters  water).  The  acid  should  always 
be  measured,  but  if  more  convenient  the  water  can  be  weighed  in 
pounds  if  it  is  remembered  that  453  cubic  centimeters  of  water  weigh 

2  275 

1  pound.     In  this  case     '        =5.02  pounds  of  water  needed. 

The  acid  and  wTater  can  be  mixed  in  the  acidulator  or  in  a  wrooden 
pail,  or  in  a  bright  tin  pail,  if  the  water  is  put  in  first  and  the  acid 
added  later.  After  the  proper  amounts  of  acid  and  water  have  been 
poured  into  the  acidulator,  they  should  be  thoroughly  mixed  at  once 
by  stirring  with  a  wrooden  paddle,  and  once  thoroughly  mixed  the 
normal  acid  is  always  ready  for  use.  Of  course  the  acid  should  not 
be  handled  in  galvanized  iron  or  aluminum  vessels,  as  it  will  rust 
them.  The  undiluted  acid  will  also  discolor  tinware  and  should  be 
measured  in  the  glass  cylinder,  as  directed.  The  " dilute"  acid  is 
drawn  from  the  carboy  into  a  gallon  glass  bottle  through  a  glass 
siphon,  which  is  first  filled  with  water.  The  water  used  in  the  siphon 
is  so  small  in  volume — about  1  per  cent  of  a  gallon — that  it  does  not 
noticeably  affect  the  strength  of  the  acid. 

There  is  nothing  difficult  about  the  preparation  of  normal-strength 
hydrochloric  acid  lor  use  in  cheese  making,  and  anyone  who  knows 
how  to  titrate  milk  for  acidity  can  learn  to  do  this  also.  To  test  the  cor- 
rectness of  the  work  when  completed,  transfer  two  cubic  centimeters 
of  the  acid  with  a  pipette  from  the  acidulator  to  the  porcelain  cup, 
and  titrate  it  with  the  normal  alkali  in  the  burette.  The  volume  of 
alkali  required  should  be  between  1.9  cubic  centimeters  and  2.1  cubic 
centimeters,  or,  better,  exactly  equal  to  the  volume  of  acid  used. 

The  degree  of  accuracy  required  in  this  whole  process  is  very  easily 
attained,  as  quite  satisfactory  results  will  be  obtained  in  acidulating 
milk  if  the  normal  acid  used  is  anywhere  between  0.95  and  1.05  normal. 

GENERAL   DIRECTIONS    FOR    PASTEURIZING    AND    ACIDULATING 

MILK. 

The  method  described  is  well  adapted  for  use  in  a  large  factory. 
At  a  factory  handling  two  to  three  large  vats  of  milk  daily  two  men 
should  be  employed.  The  inspection  and  weighing  of  milk  at  the 
intake  is  performed  by  one  man  while  the  other  makes  the  determi- 
tions  of  acidity  and  runs  the  pasteurizer.  After  the  milk  is  all  in 
and  pasteurized  the  two  men  work  together,  heating  up  the  vats, 


I  DDAB   (in  i  BE    I  'BOM    PASTBUBIZEJD   MILK. 

adding  the  starter,  color,  and  rennet  to  the  vats  at  Least  10  or  15  min- 
utes apart.  They  cut  1 1 1 < -  curds  in  the  Bame  order,  each  l'.")  minutes 
after  the  rennet  has  been  added,  and  -tart  the  agitators  in  cadi  curd 
on  as  cut.  The  vate  arc  heated  up  and  the  whej  is  drawn  from 
the  vats  in  the  same  order,  I  oth  men  working  together  in  putting 
the  curds  on  the  rack,  finishing  each  vat  of  curd  in  time  to  handle 
the  next . 

If  more  than  three  vat-  are  handled  in  one  factory,  additional  help 
will  be  needed,  especially  for  bandaging  hoops,  turning  cheese,  and 
other  labor. 

Where  only  one  vat  of  milk  is  handled  daily,  the  milk  is  run  first 
into  the  receiving  vat,  from  which  it  flows  into  the  pasteurizer, 
through  the  cooler,  and  into  the  chei  If  two  vats  of  milk  are 

handled  daily,  the  first  milk  received  may  he  run  into  one  cheese  vat, 
from  which  it  is  pasteurized  into  the  other  cheese  vat,  while  the  milk 
received  later  is  run  into  the  Bteel  receiving  vat,  from  which  it  is 
pasteurized  into  the  second  cheese  vat. 

If  three  or  more  vats  of  milk  are  handled  daily,  the  receiving  vat 
and  the  first  cheese  vat  are  filled  alternately  with  milk  from  the  in- 
take, and  alternately  emptied  through  the  pasteurizer  into  the  other 
cheese  vats.  It  is  only  necessary  to  Bee  to  it  that  the  Last  vat  filled 
from  the  intake  shall  he  the  receiving  vat  in  order  that  this  last  milk 
may  he  run  into  one  of  the  cheese  vats  after  pasteurization.  One  re- 
ceiving vat  is  needed  in  addition  to  the  necessary  cheese  vats  wherever 
this  process  is  used. 

MAKING    READY    TO   PASTEURIZE. 

Since  pasteurization  is  essentially  a  cleaning  process,  care  should 

be  taken  to  keep  the  make  room,  the  vats,  machinery,  etc.,  and  every- 
thing with  which  the  pasteurized  milk  comes  in  contact  as  clean  as 
possible. 

Although  milk  Hows  intermittently  from  the  weigh  cans,  it  is  de- 
sirable that  the  pasteurizer,  once  started,  shall  run  continuously,  with 
a  Bteady  milk  supply,  and  for  this  purpose  a  receiving  vat  i-  pro- 
vided. The  milk  should  he  run  into  the  receiving  vat  through  a 
strainer  which  will  remove  all  Hie-,  straw,  etc..  and  which  can  not 
by  accident  fail  t<»  work  properly.  Such  a  strainer  i-  shown  in  Plate 
Y.  It  i-  set  up  by  slipping  a  piece  of  seamless  cheese  bandage  over 
the  wooden  frame  of  the  vat  -trainer  and  placing  the  metal  part  on 
top.      The  metal  part  collect-  all  Large  piece-  of  dirt  and  prevent-  the 

milk  from  Bplashing  over  the  Bide.  The  two  thicknesses  of  cheese- 
cloth effectually  remove  liner  particles  of  dirt.  This  arrangement 
has  been  used  in  this  series  of  experiment-  for  about  two  years  and  is 
heartily  recommended.     Of  course  the  cloth  -hould  be  scalded  daily. 


OPERATION   OF   THE    PASTBXJBIZEB.  39 

The  weigh  can,  conductors,  receiving  vat,  and  pasteurizer  should 
be  washed  daily,  immediately  after  use,  and  again  rinsed  with  clear 
hot  water  before  use,  if  necessary.  The  pasteurizer  and  cooler  and  the 
connecting  pipes  should  be  washed  thoroughly  daily.  .lust  before 
starting  the  pasteurizer  each  morning  the  operator  should  rinse  nut 
the  cheese  vat  and  steam  it  by  running  steam  into  the  jacket.  The 
pasteurizer  and  delivery  pipes,  especially  those  parts  which  are  in 
contact  with  the  cooled  pasteurized  milk,  should  be  also  scalded  < li- 
st earned.  This  can  be  done  by  running  a  couple  of  pails  of  hot  water 
into  the  heating  compartment,  heating  it  there  to  180°  or  higher, 
and  running  it  over  the  cooler  without  having  any  cold  wTater  inside 
the  cooler. 

Where  only  one  vat  of  milk  is  being  pasteurized,  the  acidulator  may 
be  set  on  the  edge  of  the  vat,  but  to  avoid  moving  it,  wiien  several 
vats  of  milk  are  handled  daily,  the  acidulator  should  be  set  near  the 
pasteurizer  and  the  acidulated  milk  run  into  the  different  vats 
through  a  movable  conductor,  as  shown  in  Plate  III. 

STARTING   AND    STOPPING   THE    PASTEURIZER. 

When  milk  enough  has  been  received  to  insure  a  continuous  supply 
for  the  pasteurizer,  the  latter  may  be  started. 

First,  see  that  everything  is  in  place  and  that  the  pump  supplying 
water  for  cooling  is  running.  Set  the  pasteurizer  in  motion,  turn  on 
a  little  steam,  and  run  enough  milk  into  the  heating  compartment 
nearly  to  fill  it  so  as  to  register  its  temperature  on  the  naked  glass 
bulb  of  the  thermometer  placed  near  the  exit  to  the  cooler.  Do  not 
allow  any  milk  at  all  to  run  into  the  cooler.  If  any  does  by  accident, 
draw  it  out  and  scald  the  cooler  with  a  pail  of  hot  water. 

Open  the  steam  valve  to  the  full  running  capacity.  When  the 
thermometer  in  the  milk  registers  about  155°  start  the  milk  supply 
again  and  adjust  so  that  the  thermometer  stands  at  162°  at  the  exit 
from  the  heater.  Use  care  to  see  that  no  milk  at  all  is  allowed  to  run 
to  the  cooler  at  a  temperature  below  160°.  If  any  irregularity  occurs  in 
starting,  it  is  much  better  that  the  first  milk  should  be  heated  higher 
than  160°,  even  up  to  180°,  rather  than  that  any  portion  should  pass 
over  into  the  cheese  vat  without  reaching  1 60°.  It  will  do  no  harm  at 
all  if  for  a  few  minutes  at  first  milk  at  170°  or  180°  passes  over  into  the 
cooler,  because  this  milk  will  at  least  be  thoroughly  pasteurized,  but  if 
milk  at  140°,  or  any  temperature  below  160°,  passes  over  it  may  carry 
over  harmful  bacteria  which  may  injure  the  entire  vat  of  cheese.  A 
file  mark  on  the  steam-valve  handle  is  a  great  help  in  quickly  adjust- 
ing the  steam  supply  to  the  right  point. 

Once  adjusted,  and  with  steady  milk  and  steam  supply,  the  pasteur- 
izing temperature  remains  nearly  constant  and  requires  only  momen- 


In  CHiM'Ai:   cm. i.si.    ri:...M    PA8TBUBIZED    MILK. 

ia  iy  inspection  <-\  ery  few  minutes.  No  doubt  an  automatic  tempera- 
ture-controlling device  < -< » » 1 1*  1  be  used  to  advantage  here. 

Although  the  thermometer  now  supplied  with  some  forms  of 
i-  metal  jacketed  1<>  prevent  breakage,  yet  in  all  the 
experiments  here  reported  this  metal-cased  thermometer  was  found 
to  register  more  slo*  ly  than  a  naked  glass-bulbed  thermometer,  sel  in 
a  rubber  stopper,  The  latter  kind  has  been  in  use  two  years  without 
breaking  and  is  therefore  preferred. 

In  stopping  tlit*  pasteurizer  for  any  reason,  the  operator  should 
remember  to  st:>]>  the  acidulator  first,  then  the  milk  supply,  and  last 
of  all  the  Bteam.  If  the  stoppage  is  for  1  < •  1 1 lt .  as  at  the  end  of  the 
day's  run.  the  hot  milk  in  the  heating  compartment  is  drawn  out  in  a 
pail  (its  temperature  ^1  »<  m  l<i  lie  160  of  above)  and  added  t<>  the  vat. 
The  milk  in  the  cooler  is  also  drained  and  rinsed,  if  desired,  into  the 
vat . 

The  water  Bupply  for  cooling  must  be  ample  so  that  a  thermometer 
placed  in  the  milk  flowing  from  the  cooler  is  not  above  85c  at  any 
time,  and  preferably  at  80°  or  lower.  since  the  milk  in  the  vat  can 
easily  be  heated  to  85°  86?  for  setting  with  rennet,  but  can  not  BO 

Well  he  set,  or  easily  cooled,  if  ahove  .S(j°. 

STAIMI.M;    AND    STOPPING    THE    A(  IIKLATOR. 

As  Boon  as  the  pasteurizer  has  he. mi  Btarted  and  regulated  the 
pinchcock  at  the  acidulator  is  opened,  allowing  one  or  more  small 
streams  of  hydrochloric  acid  to  run  into  the  milk.  The  height  of  the 
liquid  in  the  acidulator  should  be  marked  on  the  glass  BCale  with  a 
pencil  or  string,  when  starting,  and  another  mark  placed  lower  down 
on  the  scale  t'>  show  how  much  acid  is  to  he  drawn  out  for  that  vat 
of  milk.  By  this  means  the  operator  can  see  from  any  part  of  the 
room  when  the  acidulator  is  ready  to  lie  B topped.  Always  stop  the 
acidulator  before  Btopping  the  milk. 

THE   USE   OF   BACTERIAL   STARTER   IN    THE   NEW   PROCESS. 

Tin:     REASON     FOB     ADDING     BTABTEB     IN     MAKING     LAsTLl  Ll/.Lh-M  ILK 

(  REESE . 

The  addition  of  the  required  amount  of  hydrochloric  acid  to  milk 

raises  its  acidity  at  once  to  0.25  percent,  hut  does  not  cause  any  fur- 
ther increase  of  acidity  at  any  time.  Of  the  acid  thus  added,  only 
about  one-fortieth  remains  in  the  curd,  the  rest  escaping  in  the  whey. 
No  chemical  method  has  b<  *  n  found  for  increasing  the  acidity  of  a  curd 
on  the  rack,  so  that  if  a.  id  pi  ivs  any  important  part  in  the  cheoc- 
curing  process,  it  will  he  necessary  to  add  bacteria  to  the  milk  in  order 
to  develop  the  necessary  acid  in  the  curd  and  cheese.     A  number  of 


THE   USE   OF   BACTI.UIAI.   STARTER. 


41 


experiments  were  performed  in  which  the  milk  supply  was  divided 
and  made  up  in  different  vats,  using  different  proportions  of  starter. 
The  cheese  was  finally  scored  by  Mr.  J.  \Y.  Moore  with  the  following 

results: 


Table  16. — Quality  of  cheese  made  from  pasteurized  milk  with  varying  amounts  of  starter 

added. 


Date, 
made. 


1908. 
Aug.  17 


31 


£ept  1 


Chees  i 
No." 


1076c 

1079 

1081 

L083 

1085c 

1087 

1S89 

1091 

1093c 

1095 

1097 

1099 

1101c 

1103 

1105 

1109c 

1111 

1113 

1115 

1117c 

1119 

1121 

1123 

1157c 

1159 

1161 

1163 

1165c 

1167 

1169 

1170 

1173c 

1175 

1177 

U79 

1024 

1026 


Propor- 
tion of 
starter. 


Per  cent. 


None. 
.3 


3.0 
5.0 


Tempera 
ture  of 

pasteuri- 
sation. 


;•'. 


0. 25 

157 

.50 

157 

.75 

157 

.  25 

157 

.50 

157 

.75 

157 

.25 

157 

.50 

157 

.75 

157 

.25 

157 

.75 

157 

.75 

157 

1.00 

157 

1.25 

157 

.75 

157 

1.00 

157 

1.25 

157 

None. 

162 

.3 

162 

•  6 

162 

None. 

162 

.3 

162 

.6 

162 

162 

162 
162 


Flavor.      Texture. 


40.50 
40.50 
41.25 
42.50 
41.00 
41.75 
41.00 
40.25 
40.. 50 
41.25 
42.50 
42.75 
41.25 
42.50 
42.25 
40.75 
42.25 
42.50 
42.50 
39. 50 
42.25 
41.75 
42.25 
41.00 
41.00 
42.50 
42.  .50 
39.00 
40.50 
42.00 
42.50 
40.00 
41.00 
41.00 
41 .  50 
Sour. 
Sour. 


27.00 

27.  •_'.-, 
27.25 
28.00 
27.25 
27.75 
27.25 
27.00 
27.00 
27.00 
27.75 
28.00 
27.00 
28.25 
27.75 
27.00 
27.25 
27.25 
27.75 
27.25 
27.00 
27.25 
27.00 
27.00 
27.00 
28.00 
28.00 
28.50 
26.00 
27.50 
28.00 
27.00 
26.00 
27.00 
27.00 

Color-cut. 

Color-cut. 


1  "c"  In  this  column  indicates  raw-milk  cheese. 

These  scores  may  be  summarized  as  follows: 

Table  17. — Summary  of  scores  in  Table  16. 


Amount  of  starter. 

Number 

of  cheeses 

scored. 

Average  scores. 

Flavor. 

Texture. 

Combined. 

Per  cent. 
0 
0. 25  to  0. 30 
.5    to    .6 
.75 
1.0 
1.25 

3 

6 
6 
2 
2 

40. 83 

41.04 

41.  ^ 

42.  04 
42.  12 
42.37 

26.33 
27.53 
27.54 
27.50 
27.25 
27.37 

67.  IB 
C9.18 
69.42 
69.54 
69.37 
69.75 

12  I      SDDAB   CHEESE    iiaeM    PAS  I  l.i  i;l/.i.h   mii.k. 

'I'll,  68  indicated  that  the  cheese  obtained  by  three-fourths, 

one,  <>r  one  and  ;t  quarter  per  cent  Btarter  are  about  equally  good, 
considering  both  flavor  and  texture,  and  the  use  of  three-fourths  per 
cent  Btarter  has  been  continued  Bince  August,  1908,  to  the  present 
time,  with  good  results.  Tin*  Btarter  used  Bhould  be  first  da--  in 
quality,  just  beginning  to  thicken,  containing  the  maximum  number 
<»f  lactic  acid  bacteria  in  active  condition,  and  free  from  all  objection- 
able germs  or  flavors. 

Only  a  Btarter  above  criticism,  such  as  every  g 1  cheese  maker 

should  know  how  to  prepare,  can  be  used  with  pasteurized  milk.  If 
the  starter  is  :>t  all  tainted  it  i-  Bure  t<»  damage  the  flavor  of  the  cheese 
►me  extent.  With  raw,  badly  tainted  milk,  especially  in  warm 
weather,  a  Btarter  of  only  fair  quality  will  often  greatly  improve  the 
quality  of  a  vat  of  cheese,  but  pasteurized  milk  i-  freed  from  practi- 
cally all  taints  by  the  pasteurization,  and  to  such  milk  only  tlie  best 
starter  can  Bafely  be  added. 

The  importance  of  a  good  Btarter  was  made  apparent  when,  begin- 
ning June  .».  1910,  nine  days'  make  of  pasteurized-milk  cheese  proved 

to  he  gassy  and  oil'  flavor,  and  bacteriological  examination  of  the 
starter  as  well  as  of  the  cheese  demonstrated  the  presence  of  the  same 
gas-forming  organism  in  both.  Jt  was  (dear  that  the  organism--  in 
question  did  not  pass  through  the  pasteurizer,  since  their  thermal 
death-point  was  found  to  be  lower  than  the  pasteurization  tempera- 
ture (160°)  employed  in  the  process.  Therefore  there  could  be  no 
doubt  that  the  improper  preparation  of  milk  for  propagating 
"startoline"  was  the  cause  <>(  the  trouble  in  this  case. 

A    PRACTICAL   STERILIZES    FOR    THE    CHEESE    FACTORY. 

The  essential  equipment  for  propagating  a  starter  i-  some  Bort  of  a 
Sterilizer,  an  incubator,  and  a  supply  of  a  do/en  pint  cream  bottles 
which  are  best  provided  with  fairly  tight  tin  covers  about  '2  inches 
dee]).  Various  different  Bterilizers  have  been  recommended,  the  sim- 
plest being  an  inverted  tin  pail  covering  the  bottles  of  milk  on  the 
Steam  table.  For  use  as  an  incubator,  a  small  covered  shotgun  can 
may  be  Bteamed  out  daily,  and  after  placing  the  bottles  therein  ami 
adjusting  the  cover  it  may  be  carried  to  the  ice  box.  the  cellar,  a  hay 

cooker,  or  any  room  of   suitable  temperature.     Where  bottle-  of 

-tarter    must    be   handled    and    carried    about    there   is    always    some 

danger  of  their  becoming  infected,  and  this  can  only  be  prevented  by 
intelligent  work  on  the  part  of  the  operator.  On  account  of  it-  small 
>i/.e  a  culture  propagated  in  a  bottle  is  often  called  a  "startoline," 
meaning  a  little  Btarter.  A  combined  sterilizer,  cooler,  and  incubator 
made  of  galvanized  iron  ha-  been  devised,  and  used  in  our  work 
during  the  past  year  with  entire  satisfaction.     Its  use  saves  time  in 


I'KKIWKA  THIN     n|       I  III.    SI  Mil  KK. 


43 


handling  and  reduces  the  danger  of  contamination  to  a  minimum. 

It  is  shown  in  figure  1 . 

The  apparatus  consists  of  a  galvanized-iron  container  with  cover, 
a  movable  false  bottom,  and  with  steam,  water,  and  drain  connections. 
Where  pint  bottles  are  used,  the  perforated  shelf  is  raised  and  set  on 
lugs  as  shown.  If  quart  bottles  are  used,  the  perforated  bottom  is 
lowered,  so  thai  the  top  of  the  bottle  always  stands  at  the  top  of  the 
sterilizer. 


COVER 


FALSE  BOTTOri-v£  *ROUND  COcrr 


■96 


Cap  for 

mm  BOTTLE 


CAP  FOR 

water  bottle: 


3  NOTGHE5  £  *i 
Fig.  1.— Combined  sterilizer,  cooler,  and  incubator  for  cheese-factory  starter. 


PREPARATION  OF  THE  STARTER. 

The  bottles  having  been  cleaned  and  filled  nearly  full  with  the 
best  whole  milk  obtainable  are  each  covered  with  a  tin  cap  and  set  in 
the  sterilizer,  together  with  one  bottle  of  water  carrying  the  ther- 
mometer. The  lid  is  put  on  and  the  steam  turned  on  very  slowly  at 
first,  by  turning  handle  a.  After  the  thermometer  projecting  through 
the  small  hole  in  the  lid  shows  that  the  contents  of  the  bottles  are 
heated  to  200°  or  above,  the  steam  is  left  running  for  three  quarters 
of  an  hour,  and  then  turned  off.  To  cool  the  bottles  of  sterilized  milk 
open  valve  b  and  slowly  run  in  cold  water,  which  escapes  at  the 
overflow  c.     If  the  water  is  turned  on  by  mistake  faster  than  the 


1  1  OB  BDDAB    <  HEESE    I  BOM    PAfil  BUBIZED    .MIl.K. 

overflow  <-an  <;ni\  it  off,  the  tin  caps  will  keep  it  from  entering  the 
bottles  of  milk.  When  the  thermometer  Bhowa  thai  the  bottle  con- 
tents are  cooled  to  about  To  the  water  may  be  turned  nearly  or 
entirely  off.  The  bottle  of  "startoline"  from  the  previous  day, 
which  has  uot  yet  been  opened,  is  now  brought  in  and  a  portion* 
about  a  tablespoonful  by  guess,  is  poured  into  each  bottle  of  newly 
Bterilized  milk  in  the  apparatus,  lifting  the  tin  caps  For  an  instant  for 

this  purpose.     The  n i  should  be  free  from  drafts,  floating  dust, 

or  other  source  of  contamination,  and  the  transfer  should  be  made  as 
quickly  and  carefully  as  possible.  The  cap  is  then  replaced  and  the 
cover  put  on.  The  temperature  of  the  water  can  be  kept  between 
60    and  70    for  a  leu  bours,  and  in  the  evening,  in  summer,  if  the 

weather  i-  \  cry  warm,  a  piece  of  ice  e;in  be  added  to  the  water. 

This  daily  process  of  propagating  the  "startoline"  was  performed 

in  the  cheese  factory  during  the  year  1(.»11  by  Mr.  A.  T.  Bruhn,  with 
entire  success,  carrying  along  the  same  culture  of  bacteria  throughout 
the  year.  Each  day  after  inoculating  the  fresh  bottles  of  milk,  the 
remainder  is  examined  hy  pouring  out  a  little  in  a  teaspoon  or  cup, 
to  he  tasted  and  smelled  t->  Bee  that  it  i->  in  good  condition;1  ami  if  so, 
the  remainder  in  the  jar  i^  used  in  making  up  starter  for  the  next 
day's  cheese  vat    in  the  following  manner: 

To  prepare  starter  from  this  u startoline,*'  place  in  a  shotgun  can 
about  eight  or  nine  pounds  of  milk  for  each  thousand  received  daily, 

cover  up,  and  heat  in  a  tub  or  dee])  pail  of  water  by  passing  steam 
until  the  water  is  boiling  and  a  thermometer  in  the  milk  reads  at  least 
1  so  .  Keep  it  at  this  temperature  for  three-quarters  of  an  hour  and 
then  cool  by  filling  the  tuh  with  cold  water.  A  dash  stirrer  whose 
handle  is  slipped  through  the  smallest  possible  hole  cut  in  the  cover 
i-  a  convenience  and  saves  opening  the  can  for  stirring.  When  thor- 
oughly co«»l  about  70  add  to  the  contents  of  the  can  the  remain- 
ing contents  of  the  "startoline"  jar.  as  Mated  above.      Stir  this  well 

and  leave  for  five  or  six  hours  at  this  temperature,  after  which  it 
may  he  put  in  a  cooler  place  to  stand  overnight. 

The  general  principle  on  which  the  temperature  of  starters, 
etc..  is  regulated  is  that  the  starter  should  ripen  only  fast  enough  bo 
0  he  barely  thick,  or  just  getting  thick,  when  required  for  use 
next  day.  If  the  acidity  increases  too  rapidly  at  first,  the  bacteria 
are  kept  too  Long  before  use  in  a  highly  acid  medium,  not  favorable 
to  their  growth,  and  in  general  this  i>  to  he  avoided.  The  thickening 
of  the  milk  at  about  (i()°  or  70  may  be  taken  as  an  indication  that 
the  acidity  is  in  the  neighborhood  of  six-tenths  per  cent,  which  is 
about  as  high  as  it  ought  to  go  for  this  purpose. 

To  control  the  temperature  for  ripening  is  not  so  likely  to  he 
troublesome  as  to  avoid  getting  dirt  and  foreign  bacteria  into  the 
••  Btartoline "  .»r  starter  after  it  has  l>e<  n  once  thoroughly  sterilized. 

irtber  the  quelitj  of  the  .^tai-wr.  a  bottle  of  the  thickened  milk.  unshaken  and  unopened,  may 

.mi  |  la.  »•  for  .i  dft]  oi  tv  .      •  , .  lop. 


TIMI-:    SCHEDULE    FOR    MAKINH    CHEESE. 


45 


Strictly  speaking  it  is  impossible  fco  Bterilize  milk  so  perfectly  .-is  to 
kill  all  spores  by  one  such  beating,  and  on  this  account  attention 
should  be  given  bo  selecting  the  host  possible  milk  for  starter  making. 

At  the  beginning  of  the  season  a  small  bottle  of  bacteria]  ■tarter 
can  be  obtained  from  dealers  or  from  a  college  of  agriculture. 

It  is  well  to  begin  propagating  the  starter  several  dux*  before 
cheese  making  is  to  begin,  and  also  to  carry  along  two  or  more  starters 
from  different  sources,  separately,  in  order  that  if  one  is  lost  or  found 
unsuitable  another  may  be  at  hand. 

METHOD    OF    MAKING    CHEESE    BY    THE    NEW    PROCESS. 
GENERAL    ARRANGEMENT    OF    SCHEDULE. 

In  making  cheese  by  the  new  method  the  cheese  maker  is  relieved 
of  a  great  deal  of  the  uncertainty  winch  attends  cheese  making  by 
the  ordinary  methods.  Having  inspected  the  milk  at  the  intake  and 
rejected  any  that  is  curdled  or  otherwise  unfit  for  use,  he  determines 
by  means  of  Manns's  acid  test  the  acidity  of  the  entire  vatful  of 
mixed  milk.  This  may  be  anywhere  from  0.14  to  0.25  per  cent,  or 
even  a  little  higher,  but  if  much  above  0.28  per  cent  the  milk  is  likely 
to  curdle  and  clog  the  pasteurizer.  He  then  runs  the  milk  through 
the  pasteurizer  and  adds  to  the  cold  milk  as  it  flows  into  the  cheese 
vat  enough  dilute  hydrochloric  acid  to  raise  the  acidity  of  the  whole 
vat  to  just  0.25  per  cent  (calculated  as  lactic  acid).  Three-quarters 
per  cent  of  a  first-class  starter  is  added,  and  after  heating  to  85°  the 
color  and  rennet  are  stirred  in  immediately. 

The  rest  of  the  process  is  conducted  according  to  a  fixed  time 
schedule,  which  is  never  varied.  The  time  from  adding  rennet  to 
hooping  the  curd  is  always  exactly  five  hours  and  fifteen  minutes, 
and  the  intermediate  process  is  as  shown  in  Table  18.  Tins  is  carried 
on  every  day  in  the  season  without  exception. 

While  it  may  be  found  desirable  or  convenient  at  some  factories 
to  modify  somewhat  this  routine,  described  below,  yet  it  appears 
practically  certain  that  whatever  routine  of  operations  is  adopted 
at  any  factory,  it  can  be  followed  without  modification  throughout 
the  season. 

Table  18. —  Time  schedule  for  making  cheese  by  the  new  method. 


Operation. 


Time  inter- 

val between 

operat 

ons. 

//. 

m. 

0 

0 

0 

25 

0 

15 

0 

20 

1 

25 

1 

30 

1 

00 

0 

20 

Total  time 
after  add- 
ing rennet. 


Adding  rennet 

Cutting  the  curd 

Beginning  to  heat 

Turning  off  steam 

Placing  rack  after  drawing  whey 

Milling  the  curd 

Salting  the  curd 

Hooping  the  curd 


777. 

0 
25 
40 
60 
25 
55 
55 
15 


46  CHEDDAB   OHEESE    I  BOM    PAS!  EURIZED    Mil .K. 

For  example,  if  the  rennet  were  added  to  the  milk  at  exactly  0 
o'clock  the  cunl  would  !><•  ready  t<>  put  in  1 1 1<-  hoops  five  hours  and  fif- 
teen minutes  later,  i.e.,  at  2.15  in  the  afternoon.  As  soon,  as  the  rennet 
is  added  it  is  best  to  have  ■  written  schedule  showing  the  time  when 
each  operation  should  be  performed.  Having  once  learned  how  to 
perform  each  operation  in  this  method  of  cheese  making  it  is  only 
aar}  to  do  everything  in  as  uniform  manner  as  possible  in  order 
to  get  satisfactory  results  daily  throughout  the  season.  There  is 
never  ;m\  need  to  hurry  the  process  if  the  milk  was  overripe  at  the 
beginning,  because  the  lactic-acid  bacteria  are  practically  all  killed 
by  tin1  pasteurization.  The  Bame  is  also  true  of  the  gas-forming 
bacteria,  bo  there  is  no  time  Lost  in  working  gas  out  of  the  curd. 
There  is  no  reason  for  waiting  to  ripen  the  milk  at  the  beginni 
the  process  before  adding  rennet. 

i  \moi:m  PROPORTION  <>f  COLOB   i  BED  i\   L911,   wi>  i:i:wi.i    REQ1  [RED. 

Color.     Throughout  the  season  of  1911  two-thirds  of  an  ounce  of  a 

standard  make  of  cheese  color  per  thousand  pounds  of  milk  was  used, 

giving  the  cheese  a   medium  shade  of  color.     These  cheeses  were 

shipped  into  a  number  of  different  cities  and  appeared  satisfactory 
to  dealers  in  all  parts  of  the  country,  except  in  Philadelphia,  Pa., 
and  Boston,  Mass..  where  some  dealers  asked  for  white  and  others 
for  highly  colored  cheese,  a-  is  Bhown  by  the  following  extracts  from 
letters.  Where  more  than  one  extract  appears  from  the  same  city 
they  are  from  different  dealers. 

Our  market  usee  white  cheese  exclusively. 

■i.  Mm as Use  both  white  and  colored. 

Boston,  Ma  — \  very  light  color  would  not  do  for  this  market. 

Chicago,  111 No  comment  on  color. 

Fond  du  Lac,  Wis V  little  too  light  color. 

( leneva,  X.  Y No  comment  on  color. 

Marahfield,  Wia No  comment  on  color. 

Minneapolis,  Minn No  comment  on  color. 

New  York,  N    V ( lolor  is  exactly  right. 

York,  X.  V should  be  a  trifle  higher  color. 

Philadelphia,  Pa Eave  to  have  white  cheese  for  Philadelphia. 

Plymouth,  W  i- No  comment  on  color. 

Sheboygan,  Wia \  good  commercial  color,  but  might  stand  a  iritle  more  color. 

Bhebo}  gan,  Wia No  comment  on  color. 

llis,  M" No  comment  on  color. 

Washington,  I'.  I   Most  of  our  customers  want  it  colored. 

Waterloo,  Wis No  comment  on  color. 

"Rennet.  The  Bame  proportion  <>f  rennet  is  always  used  in  this 
process,  because  the  milk  is  always  in  the  Bame  condition  as  to  acidity 
at  the  time  of  adding  rennet .  and  always  ripen-  equally  fast  afterwards. 

Therefore,   having  once  selected    the   most    Buitable  proportion   <>f 

rennet,  there  is  no  reason  for  changing  it.     The  use  of  2  ounces  of 


ADDING    STABTEB,   COLOR,    \M>    RENNET.  47 

Hansen's  or  MarschalTs  rennet  per  thousand  pounds  of  milk  is  adopted 
as  the  best  practice,  since  this  quantity  produces  visible  coagulation 
in  7  minutes,  as  shown  in  Table  2,  and  the  curd  is  in  prime  condition 

for  cutting  in  25  minutes  after  adding  rennet.  If  the  rennet  extract 
is  weaker  than  it  should  be,  such  amounts  should  be  used  as  will 
cause  coagulation  in  the  time  stated. 

If  a  larger  proportion  of  rennet  than  2  ounces  per  thousand 
pounds  were  used,  there  would  hardly  be  time  for  the  milk  to  become 
quiet  before  visible  thickening  began,  and  the  curd  might  be  damaged 
and  broken  through  thickening  while  still  in  motion.  On  the  other 
hand,  over  two  years'  experience  with  the  method  has  shown  that 
there  is  no  need  for  using  a  smaller  proportion  of  rennet  than  2 
ounces.  Good  cheese  can  be  made  with  1  ounce  of  rennet  per 
thousand  pounds  of  milk,  but  the  coagulation  of  the  milk  is  unnec- 
essarily slow. 

As  in  regular  cheese  making,  great  care  must  be  taken  not  to 
measure  or  dilute  rennet  extract  in  any  container  in  which  there  is 
present  the  least  trace  of  cheese  color,  because  the  cheese  color  is 
strongly  alkaline,  and  rennet  loses  its  coagulating  power  almost 
instantly  when  in  contact  with  alkalies. 

ADDING    STARTER,  COLOR,  AND    RENNET   TO   THE    MILK. 

The  temperature  of  all  the  mixed  milk  after  pasteurizing  is  never 
above  85°  and  commonly  only  70°  to  80°.  The  acidity  may  be 
tested,  if  desired,  and  should  be  just  0.25  per  cent,  or  between  0.24 
and  0.26  per  cent.  Three-quarters  of  a  pound  of  starter  per  hun- 
dredweight of  milk  in  the  vat  is  added  immediately  through  a  hair 
sieve,  stirring  the  milk.  The  rake  is  then  put  in  and  the  vat  stirred, 
while  heating  up  to  85°.  The  desired  amount  of  color  is  stirred  in, 
and  always,  without  exception,  the  rennet  is  stirred  in  last  of  all. 
The  rennet  extract  measured  out  for  5,000  pounds  of  milk  should  be 
diluted  in  a  pailful  of  water.  In  adding  rennet,  first  stir  the  milk 
across  the  vat  the  short  way,  going  rapidly  from  one  end  of  the  vat  to 
the  other.  With  the  largest-sized  vats,  two  men  with  rakes  may 
begin  at  the  middle  and  walk  toward  the  ends  while  stirring.  Then 
walk  back  along  the  vat,  adding  the  diluted  rennet  from  a  pail  to  the 
milk  which  is  still  in  vigorous  motion,  noting  on  the  clock  the  instant 
when  the  rennet  first  enters  the  milk.  Set  down  the  pail  and  again 
stir  the  milk  across  the  vat  the  short  way,  with  the  rake  or  rakes,  for 
exactly  one  minute,  in  which  time  the  operator  should  be  able  to 
walk  up  and  down  the  vat  three  or  four  times.  In  this  way  the 
smallest  as  well  as  the  largest  vats  of  milk  should  be  set.  Take  out 
the  rakes  promptly  one  minute  after  the  rennet  entered.  Cover  the 
vat  at  once,  and  leave  undisturbed.  No  top  stirring  is  necessary  or 
permissible,  as  the  milk  begins  to  thicken  almost  exactly  seven  min. 


48  CHEDDAB   CHEESE    PBOM    PASTEURIZED    MILK. 

slier  adding  rennet,  before  there  is  any  visible  cream  rising. 
Follow  exactly  the  directions  as  to  temperature,  acidity,  and  propor- 
tion of  rennet  every  day  in  the  season. 

CUTTING,  STIBRINGj    wi>    in.  \  I  i\o    THE   CUBD. 

The  curd  formed  in  this  process  Is  always  ready  to  cul  exactly  25 
minutes  after  the  rennet  entered  the  milk.  Therefore  as  soon  as  the 
rennet  has  been  added  it  is  best  for  the  operator  to  write  the  entire 
time  schedule,  as  shown  in  Table  Is.  For  the  rest  of  the  day's  work 
on  a  paper,  or,  better,  on  a  blackboard,  which  can  be  seen  across  the 
room.  Some  operators  may  suppose  that  possibly  the  curd  might 
l>e  cut  a  little  earlier  or  later,  but  experience  has  Bhown  that  the  curd 
is  always  in  a  thoroughly  satisfactory  condition  for  cutting  just  25 
minutes  after  adding  rennet.  There  is  therefore  no  need  for  repeated 
testing  of  the  curd  with  the  finger;  it  is  only  necessary  to  keep  an 

eye  on  the  clock,  and  follow  the  t  ijne  >chedule. 

In  cutting,  begin  with  the  horizontal  knife  and  cut  lengthwise  <>f 
the  vat :  t  hen  use  t  he  vert  ical  knife  across  t  he  vat .  cnt  t  ing  alternately 
toward  and  away  from  the  operator.  Finally  cnt  Lengthwise,  with 
the  vert  ical  knife.     Do  not  cnt  the  vat  more  than  once  in  each  direc- 

t  inn,  and  t  ry  to  do  t  he  cnt  t  ing  in  exactly  t  lie  same  manner  every  day. 
The  different  cuts  should  not  lap,  nor  should  portions  of  the  curd 
wider  than  three-eighths  of  an  inch  he  left  uncut  between  the  knives, 
except  in  the  following  case:  In  cutting  next  to  the  sides  of  the  vat, 
a-  in  the  first  and  last  cuts  in  each  direction,  hold  the  knife  as  close 
to  the  metal  sides  of  the  vat  as  possible.  If  the  knife  doe- not  appear 
wide  enough  to  cnt  the  remaining  curd  at  the  last  stroke,  cut  close  to 
the  tin  and  leave  a  narrow  strip  of  uncut  curd,  not  at  tin1  edge  of  the 
vat,  hut  between  the  last  cut  and  the  next  to  the  last.  This  strip 
will  he  cut  more  thoroughly  by  the  knives  moving  in  other  directions 
than  if  it  had  been  left  next  the  tin.  Knives  with  hlades  three-eighths 
of  an  inch  apart  are  required  for  this  method. 

Immediately  after  cutting  put  tin4  agitator  hlades  in  place  and 
Mart  them  in  motion.  The  curd  obtained  in  this  process  is  so  firm 
and  solid  that  this  can  always  he  done  safely.  Go  around  the^vat 
with  the  hand  some  t  hue  during  the  next  15  minutes,  loosening  the 
eurd  From  the  sides,  bottom,  and  corners  of  the  vat.  A  form  of  agi- 
tator which  is  very  satisfactory  has  one  pair  of  revolving  hlades 

which    also    move   up   and    down    the   vat.   somewhat    resembling   the 

mot  i<>n  of  t  he  rake. 

Bxacl  ly  15  minutes  after  cutt  big  turn  steam  into  the  jacket  of  the 
vat ,  and  raise  the  temperat  ure  gradually  during  the  next  2(1  minui 

just  !!•    to  104° — which  temperature  is  maintained  until  the  whey 

is  draw  n. 


Bul.  165,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  VI. 


o 


MISCELLANEOUS   OPERATIONS  IN    CHEESE    MAKING.  49 

DRAWING    THE    WIIKY,    HATTING,    CUTTING,    AND    TURNING    THE    01  RD. 

The  agitator  is  left  running  until  about  t  wo  minutes  before  i  be  \\  bey 
is  to  be  drawn,  when  it  is  removed,  and  the  curd,  after  settling  a  few  sec- 
onds, is  pushed  slowly  away  from  the  gate  with  one  or  two  rakes.     The 

whey  strainer  is  placed  inside  the  vat  and  the  hair  sieve  below  t  be  gate 
in  the  conductor,  the  gate  being  opened  at  such  a  time  as  will  permit 
the  whey  to  be  out  and  the  first  rack  to  be  put  in  place  at  the  time 
given  in  the  schedule.  When  the  whey  is  nearly  all  out,  the  gate  end 
of  the  vat  is  lowered  gradually,  and  a  few  seconds  later  the  curd  is 
pushed  down  toward  the  gate,  leaving  the  upper  third  or  half  of  the 
vat  bottom  bare  and  free  from  whey.  In  this  process  the  curd  is 
always  sufficiently  firmed  in  the  whey  so  as  not  to  need  any  stirring 
in  the  whey  or  on  the  rack.  With  reasonably  brisk  work  the  curd 
can  be  transferred  to  the  curd  cloth  on  the  rack  with  a  curd  pail  or 
scoop  before  it  has  time  to  become  lumpy  on  the  bottom  of  the  vat. 
Each  pail  of  curd  as  it  strikes  the  rack  should  fall  apart  loosely  and 
not  show  the  presence  of  great  lumps  of  curd  matted  together.  Any 
such  lumps  should  be  lightly  broken  up  with  the  hand,  and  if  many 
lumps  appear  it  indicates  lack  of  skill  and  quickness. 

The  curd  is  piled  evenly  on  the  rack  about  4  or  5  inches  thick, 
and  the  top  is  leveled  off  with  the  hand  in  the  usual  manner  and  cov- 
ered with  a  curd  cloth.  More  racks  if  necessary  are  put  in  place  and 
the  vat  is  finally  covered,  leaving  the  curd  to  drain.  The  little  curd 
gauge,  made  of  wood,  devised  during  the  course  of  these  experiments 
is  a  help  in  getting  the  layer  of  curd  of  the  right  thickness  and  also 
gives  a  good  square  end  to  the  curd,  which  makes  it  easier  to  cut  into 
blocks  of  uniform  shape.      (See  PI.  VI.) 

Just  15  minutes  after  the  time  scheduled  for  putting  in  the  rack 
the  curd  gauge  is  removed  and  the  cutting  of  the  matted  curd  into 
blocks  8  inches  square,  or  6  by  12  inches   is  begun. 

The  blocks  are  turned  over  immediately  after  cutting,  and  again 
turned  15  minutes  later.  They  are  then  turned  once  in  10  minutes, 
and  one  hour  after  drawing  the  whey  are  piled  two  deep,  and  repiled 
every  10  minutes  until  milled.  In  turning  and  piling,  care  is  always 
used  to  turn  the  outer  cooler  surfaces  toward  the  inside,  in  order  that 
the  entire  mass  of  curd  may  remain  at  practically  uniform  temperature 
throughout,  as  in  ordinary  practice. 

MILLING,    SALTING,    AND    HOOPING    THE    CURD. 

Exactly  one  and  a  half  hours  after  the  whey  is  drawn  the  curd  is 
milled.  The  milled  curd  is  piled  along  the  sides  of  the  vat,  so  as  to 
drain  toward  the  middle.  It  is  stirred  up  with  the  hands  from  the 
bottom,  turning  the  pile  over  about  once  every  10  minutes  after 
milling,  so  as  to  cool  it  somewhat,  prevent  matting,  and  allow  free 
79994°— Bull.  165—13 i 


50  OHBDDAB   CHEB8E    PBOM   PA8TBUBIZBD   MILK. 

drainage.  Little  or  no  white  whey  ever  escapee  from  the  curd  after 
nulling  or  Baiting  when  made  u|>  by  this  process,  although  some  clear 
w  bey  or  brine  does  drain  nw  ay, 

One  bour  after  milling  sail    i-  thoroughly  ini\<'<l  with  the  curd  at 

the  rate  of  '2  pounds  of  sail  per  hundred  <>f  curd,  which  amounts 
practically  to  2  pounds  per  thousand  of  milk  in  the  spring  and  early 
Bummer,  and  2]  pounds  per  thousand  of  milk  in  the  fall,  when  the 
yield  of  cheese  per  hundredweight  of  milk  is  Bomewhat  greater.  The 
curd  is  Btirred  overseveral  limes  during  the  next  20  minutes,  by 
which  time  the  sail  is  all  dissolved,  and  the  curd,  at  a  temperature  of 

82°  to  86°,  is  ready  to  he  hooped.      Kach    hoopful    of   curd  is  covered 

with  a  cloth  and  follower  as  soon  as  filled,  in  order  to  prevent  the  sur- 
face of  the  curd  from  coolingSO  far  that,  it  might  fail  to  close  well  in 
the  pic— . 

It  is  of  the  utmost  importance  that  every  cheese  should  he  well 
dosed  and  develop  a  perfect   rind,  free  from  cracks  or  other  openings. 

Where  openings  occur  mold  is  sure  to  enter  during  the  curing  pro< 

and  the  flavor  especially  is  apt  to  suffer  as  a  result. 

PRESSING    AND    DRESSING    THE    CHEESE. 

Throughout  the  present  set  of  experiments  the  cheese  has  heen 
pressed  for  about  an  hour,  applying  pressure  with  the  hand  lever 
only,  and  at  first  only  sufficient  pressure  is  used  to  keep  the  drippings 
running  from  the  hoops.  After  an  hour  the  cheese  is  dressed  and 
returned  to  the  press,  when  continuous  pressure  is  put  on  and  it  is 
left  for  the  night. 

In  bandaging  the  hoops,  the  usual  starched  circles  are  used  under 
the  heavy  muslin  or  duck  cap  cloths,  or  if  it  is  found  that  the  circles 
are  hard  to  remove  for  paraffining  they  may  he  left  out  and  the  cap 
cloths  left  on  the  cheese  until  paraflined.  The  cap  cloths,  being  of 
heavy  cloth,  can  be  stripped  ofT  rapidly  without  tearing  and  washed; 
in  this  way  they  may  be  used  many  times.  The  next  morning  it  is 
customary,  as  in  cheese  factories  generally,  to  look  over  the  cheese, 
Btraighten  any  bandages  which  may  be  faulty,  and  turn  any  crooked 
cheese  over  in  the  press,  leaving  them  until  noon  to  straighten. 

DRYING,    PARAFFINING,    AND   CUBING. 

The  cheeses  when  taken  from  the  press  are  stenciled  witli  the  brand 
and  date  of  making  or  a  reference  number,  and  placed  on  shelves  in  a 
well- vent  dated  room  to  dry  on  the  surface.  This  room  may  be  as 
high  as  70°.      Mere  they  are  turned  over  once  a  day. 

The  cheese  Bhould  be  paraffined  when  5  to  10  days  old.  or  pos- 
sibly  earlier.     The  paraffin  should  be  at  220°  F.,  at  Least,  and  better  at 


MISCELLANEOUS   OPERATIONS  IN   OHBESB    MAKING.  51 

230°  to  250°  F.  The  thinnest  possible  coal  of  paraffin  is  the  best, 
and  the  cheese  should  be  held  in  the  paraffin  aboul  5  seconds  and 
then  drawn  out  and  left  to  drain  over  the  vat,  OH  a  rack,  until  it  can 
bo  handled.  A  thin  coating  of  paraffin  is  llcxihlc  and  Jess  likely  to 
crack  than  a  thick  coating. 

It  is  possible  to  euro  this  eheose  at  any  temperature  between  '.l 
and  75°.  When  it  is  desirable  to  cure  the  cheese  as  fast  as  |><»-il>lr, 
a  temperature  of  75°  may  be  used  without  injury  to  the  quality. 
However,  at  this  temperature4  there  is  considerable  shrinkage,  and  it 
is  necessary  to  wipe  the  cheeses  occasionally  and  turn  them  over  to 
prevent  them  from  getting  moldy  and  sticking  to  the  shelves. 

At  45°  to  55°  the  cheese  cures  well,  with  little  shrinkage  and  a 
minimum  amount  of  labor.  It  also  cures  well  when  stored  at  34° 
at  the  age  of  1  week  and  develops  little  or  no  mold  on  the  surface, 
but  owing  to  the  extra  cost  this  temperature  should  only  be  employed 
where  it  is  necessary  to  hold  the  cheese  for  a  considerable  length  of 
time. 

BRANDING    AND    SELLING    THE    CHEESE. 

In  order  that  customers  may  be  sure  that  they  are  getting  genuine 
pasteurized-milk  cheese  when  called  for,  every  cheese  should  be 
marked  with  the  words  "Pasteurized  cheese'7  running  all  round  the 
edge  of  the  cheese.  All  persons  making  cheese  according  to  the  process 
here  described  should  use  such  a  brand,  in  order  to  distinguish  this 
product  from  the  ordinary  Cheddar  cheese.  A  large  number  can 
be  rapidly  marked  with  a  rubber  stamp  or  by  rolling  the  cheese  over 
rubber  type,  set  in  a  board,  as  shown  in  figure  2.  Narrow  strips  of 
wood  on  each  side  of  the  board  prevent  the  cheese  from  rolling  side- 
wise  off  the  type. 

In  a  new  style  of  product  uniformity  is  a  quality  which  consumers 
and  dealers  require.  It  is  recommended  that  the  maker  of  this  style 
of  cheese  keep  back  one  cheese  from  each  day's  make,  when  shipping, 
until  the  consignment  has  been  accepted  and  paid  for  by  the  buyer. 
The  sample  cheese  can  then  be  sent  along  with  the  next  shipment 
without  plugging.  If  necessary,  the  cheese  can  be  plugged  with  a 
trier,  and  by  this  means  the  maker  will  be  able  to  study  any  faults 
which  may  be  observed  by  the  buyer  and  avoid  them  in  the  future. 
Names  of  leading  cheese  dealers  who  have  already  received  sample 
shipments  of  this  make  of  cheese  and  found  it  suitable  for  their 
trade  may  be  obtained  from  the  authors. 

Where  a  maker  doubts  whether  the  buyer  is  giving  him  fair  treat- 
ment, it  is  recommended  that  parts  of  each  day's  make  be  sent  to 
two  different  dealers,  whose  criticisms,  if  any  are  received,  can  be 
compared  by  the  maker  at  the  factory. 


CHEDDAR    CHEESE    FROM    PASTEURIZED    MILK. 


TESTING    CHEESE     FOB    MOISTURE    WHEN     DRESSED    IN    THE    HOOP. 

In  making  cheese  by  this  process,  the  green  cheese  was  found  to 
differ  very  little  in  moisture  content  from  day  to  day.  as  is  Bhown  in 
Table  19  Excepting  the  first  day  the  cheese  was  made  each  day  in 
two  rats,  and  each  \  at  of  curd  was  tested  for  moisture  separately. 

The  determination  of  moisture  in  cheese  is  not  recommended  as  a 
pari  of  the  daily  work  in  a  factory.  It  is  of  great  value,  however, 
in  experimental  work,  where  it  is  desired  to  study  the  effect  on  their 
moisture  contenl  of  different  methods  of  handling  curds,  or  the  effect 
of  different  moisture  content  on  the  market  value  or  keeping  quality 
(•I  cheese. 


FlO. 


-Method  of  marking  cheese. 


Moisture  tests  are  easily  made.  It  is  objectionable,  however,  to 
plug  a  new  cheese  every  day  for  a  moisture  test  because  of  the  dan- 
ger of  admitting  molds,  etc.,  beneath  the  rind,  and  it  has  been  found 
that  plugging  the  green  cheese  can  ho  entirely  avoided  by  sampling 
it  at  the  time  it  is  dressed  in  the  hoop,  about  one  hour  after  putting  it 
to  press.  The  trier  hole  made  at  this  time  by  turning  down  the 
bandage  and  inserting  the  trier  at  the  side  will  close  entirely  over 
night  in  the  press,  leaving  the  rind  perfect.  Samples  of  cheese  thus 
taken  from  the  dressed  curd  and  tested  for  moisture  agreed  closely 
in  moisture  content  with  samples  taken  with  a  trier  from  the  same 
cheese  the  next  day.  after  pressing  about  twenty  hours,  as  may  be 
seen  from  Table  19. 

The  moisture  tests  were  all  made  by  heating  10-gram  portions  of 
the  curd    for   at    least    three   hours   in    the   Wisconsin   hidi-prossurc 


INCREASED    HELD   OF   CHEESE   OBTAINED. 


53 


steam  oven.1  After  three  or  four  hours  there  is  practically  no  Further 
loss  of  weight  from  Bamples  o(  Fresh  curd  in  24  hours'  heating.  Sam- 
ples of  cured  cheese  continue  to  lose  weighl  with  continued  heating 
much  more  noticeably  than  Bamples  of  Fresh  curd  or  green  cheese. 

Tahi.e  19. — Comparison  of  moisture  determination*  made  on  samples  taken  when 
was  dressed,  three-quarters  to  one  hour  after  pressing,  and  on  samples  taken  from  green 
cheese,  next  day,  when  removed  from  press. 


Moisture  content  when  • 

Moisture  content,  next  day, 

Dale. 

was  dressa 

. 

whtM  removed  from  pre 

DilTer- 

enee. 

First. 

Second. 

Average. 

First. 

Second. 

Average. 

1911. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Aug.   15 

37.40 

37. 5  J 

37.  ti  1 

+0.10 

16 

38.50 

38.60 

38.50 

39.00 

3s.  75 

+  .15 

16 

38.50 

3 

38.  70 

38.50 

3s.  27 

-  .43 

17 

39.10 

39.35 

38. 6J 

3s.  55 

-  .80 

17 

38.  90 

39.00 

38.95 

39.  40 

:-!'.'.  4  i 

39.  4  ) 

+  .45 

In 

37.  B  i 

37.  75 

37.  77 

37.  75 

37.  95 

37.  s", 

+  .08 

18 

42.  25 

42.  25 

42.  25 

41.25 

41.40 

41.  32 

-  .93 

23 

38.80 

3S.80 

3s.  s  ) 

38.05 

38.  4". 

38!  21 

—  . .").") 

23 

42.25 

42.  45 

42.35 

42.20 

42.  1.1 

42.  15 

-  .20 

24 

39.35 

39.  05 

39.20 

39.  70 

40.  3  ) 

4  >.().) 

24 

44.  25 

44.  3  ) 

44.  27 

43.15 

43.  3  ) 

43.  22 

-1.05 

25 

39.55 

39.  70 

39.  62 

39. 30 

39.65 

39.  46 

-  .If, 

25 

44.10 

44.4.3 

44.  27 

44.  25 

44.  95 

44.  6  ) 

+  .33 

26 

38.95 

39.10 

39.02 

:>.  S  1 

39.00 

3s.  90 

-  .12 

26 

44.30 

44.60 

44.45 

42.  -  1 

43.00 

42.  9J 

-1.55 

RESULTS  OF  TWO  YEARS"   TRIAL  OF  THE  METHOD. 
INCREASED    YIELD    OF    CHEESE    OBTAINED    BY    THE    NEW    PROCESS. 


APPARATUS    AND    METHODS    OF    STUDY. 

In  the  season  1909-1910  it  was  found  that  an  increased  weight  of 
cheese  is  regularly  obtained  after  pasteurization  as  compared  with 
the  weight  obtained  by  the  regular  factory  methods.  For  the  pur- 
pose of  accurately  studying  the  yield  of  cheese  in  1911  two  scales 
were  used,  one  of  5,000  pounds'  capacity  graduated  on  the  beam  to 
one-half  pound  and  one  of  300  pounds'  capacity  graduated  on  the 
beam  to  one-tenth  pound.  The  larger  scale  was  set  up  permanently 
in  one  corner  of  the  make  room,  and  a  wooden  frame  carrying  a  300- 
gallon  steel  receiving  vat  was  placed  upon  it.  The  outlet  of  the  vat 
is  of  sanitary  metal  piping,  suspended  by  wire  to  the  vat  in  such  a 
way  that  the  pipe  and  contents  are  weighed  each  time  with  the  vat. 
The  frame,  vat,  and  pipe  weighed  487^  pounds  when  empty.  The 
separate  weights  and  the  scale  on  the  beam  were  carefully  tested  by 
use  of  test  weights.  The  entire  set  of  weights  agreed  among  them- 
selves so  closely  that  no  difference  could  be  detected  in  the  equilibrium 
of  the  beam  when  one  weight  was  substituted  for  another  in  weighing 
a  load.     The  error  in  a  single  weighing  is  not  over  one- quarter  of  a 

JFarrington,  E.  H.    A  creamery  method  for  the  determination  of  water  in  butter.     Wisconsin  Agri- 
cultural Experiment  Station,  Bulletin  154.     Madison,  Sept.,  1907. 


54  CHEDDAB   CHEB8E    li:-»M    PA8TBUBIZED    MILK. 

pound  with  large  or  unaD  Loads.  Except  when  weighing  the  lever 
is  kepi  up,  thus  relieving  the  knife  edges  from  load  and  wear. 

The  method  of  using  this  apparatus  is  as  follows:  The  vat  being 
empty  with  the  pipes  in  place  and  Btopcocks  closed]  the  supply  of 
milk  is  run  into  the  vat  through  a  conductor  and  cloth  strainer.  The 
Btrainer  and  conductor  arc  then  removed,  the  lever  is  lowered,  and 
the  weight  of  vat  and  contents  determined.  Jt  i<  our  habit  to  balance 
the  scales  exactly,  giving  neither  "Up"  nor  ••down"  weight.  The 
lever  is  then  raised,  and  the  operator  climbs  up  the  ladder  on  the 
frame  to  the  runboard  along  the  Bide  of  the  vat.  With  a  dipper  he 
stirs  the  milk  continuously  and  vigorously  for  5  or  10  minutes,  and 
continues  Btirring  while  a  portion  i  t  the  milk  is  being  drawn  ou1  for 
use  in  one  of  the  experimental  cheese  vats.  The  vat  and  the  remain- 
ing milk  are  then  weighed  with  the  Bams  precautions  as  before,  after 
w  hieh  another  portion  of  the  milk  may  be  drawn  off  for  use  in  another 

Vat   in  the  same  manner. 

The  precautions  mentioned  above  seemed  sufficient  to  insure  that 
the  milk  used  in  the  two  vats  one  for  ordinary  and  one  for  pas- 
teurized cheese  was  thoroughly  mixed  at  the  time  it  was  drawn 
from  the  receiving  vat,  and  that  each  lot  was  weighed  accurately 
with  a  total  possible  error  of  not  over  one-half  a  pound  in  a  vat  of  200 
to  2,000  pounds  of  milk — an  error  of  one-fortieth  to  one-fourth  of 
1  per  cent,  at  most. 

The  other  new  scale  mentioned  above  is  a  counter  scale  graduated 
on  the  beam  to  one- tent  li  of  apOUnd  and  sensitive  to  one-twentieth  of  a 

pound  with  any  load  up  t  i  200  pounds.  This  was  used  for  weighing 
the  cheese  throughout  the  work  lure  described.  The  set  of  weights 
used  with  this  Bcale.  agreed  among  themselves  and  with  the  test 
weights  mentioned  above  in  the  description  of  the  other  scale. 

With  the  smaller  scale.  20  to  200  pounds  of  cheese  could  readily  be 
weighed  with  an  error  of  not  over  0.05  of  a  pound,  or  0.25  per  cent, 
at  most.  On  68  days  during  the  season  of  1911  the  receiving  vat  of 
milk  was  divided  into  two  accurately  weighed  portions  fortius  exper- 
iment.    One  of  these  was  pasteurized  and  made  up  into  cheese  by 

the  new  method,  the  othei  portion  was  made  ii]>  into  chee-e  by  regular, 

factory  methods.  The  cheese  was  I3j  inches  in  diameter  by  J  inches 
high,  the  "daisy"  Bize.  The  green  cheese  was  always  weighed  as 
quickly  a-  possible  after  being  removed  from  the  hoops.  'Die  daily 
record  of  weights  of  milk  used  and  of  cheese  obtained,  and  the  per 
cent  of  increased  yield  which  resulted  from  pasteurization,  are  shown 

in  Table  20. 


IXCHKASKD    VIK1.D    OF    C'HKKSK    OMTAINKI). 


55 


Table  20.-    Increased  yield  of  gran  elms,'  obtained  by  the  /""   method  from  pasteur- 
ized milk. 


Pasteurized  milk. 

Raw  milk. 

<;;iin  by 

Proportion  of 
tarter  used. 

Date  made. 

Yield  of 

Yield  of 

pasteur- 

cheese 

cheese 

ized 

Pas- 

Milk- 

Green 

per  hun- 

Milk 

Green 

per  hun- 

milk. 

Raw. 

used. 

cheese. 

dred- 

used. 

cheese. 

dred- 

teur- 
ised. 

weight 

weight 

of  milk. 

of  milk. 

1911 

Pounds. 

Pounds. 

Pounds. 

Pounds. 

Pounds. 

Pounds. 

Per  cent. 

Per  ct. 

Pet  a. 

Feb. 

23 

538. 0 

53.20 

9.89 

380.0 

35.40 

9.31 

6.23 

0.75 

0.00 

24 

504. 5 

51.00 

10.11 

380.0 

36.60 

9.63 

4.98 

.75 

.00 

27 

1,026.5 

106.20 

10.35 

600.0 

57.80 

9.63 

7.48 

.75 

.00 

28 

800.0 

82.20 

10.27 

400.0 

38.30 

9.57 

7.31 

.75 

.75 

Mar. 

1 

350.0 

35.40 

10.11 

510.0 

50.20 

9.84 

2.75 

.75 

1.50 

2 

389.5 

39.00 

10.01 

628.0 

59.70 

9.51 

6.61 

.75 

.75 

3 

340.0 

35.00 

10.29 

522,0 

52.30 

10.02 

2.79 

.75 

1.50 

7 

855.0 

88.20 

10.32 

380.0 

38.40 

10.11 

2.08 

.75 

2.00 

8 

590.0 

60.70 

10.29 

388.5 

39.30 

10.12 

1.68 

.75 

1.50 

9 

418.0 

42.80 

10.24 

417.5 

41.00 

9.82 

4.27 

.75 

1.00 

10 

442.0 

44.70 

10.11 

700.0 

66.40 

9.49 

6.53 

.75 

.00 

13 

1, 166.  0 

122.00 

10.46 

275.0 

25.70 

9.34 

12.00 

.75 

.00 

14 

956.0 

103.40 

10.81 

260.0 

25.80 

9.92 

8.97 

.75 

.75 

15 

570.5 

58.10 

10.18 

380.0 

37.50 

9.87 

3.14 

.75 

.75 

16 

531.5 

56.90 

10.71 

359.0 

37.40 

10.42 

2.78 

.75 

2.00 

17 

395.  0 

41.20 

10.43 

396.0 

39.80 

10.05 

3.78 

.75 

2.50 

20 

1,344.0 

136.00 

10.12 

384.0 

36.60 

9.53 

6.19 

.75 

.00 

21 

570.0 

56.40 

9.89 

378.0 

35.30 

9.34 

5.89 

.75 

.00 

22 

362.5 

36.00 

9.93 

542.0 

51.80 

9.56 

3.87 

.75 

1.67 

Apr. 

5 

585.0 

60.80 

10.39 

390.0 

37.70 

9.67 

7.45 

.75 

.75 

7 

508.0 

51.15 

10.07 

339.5 

32.50 

9.57 

5.22 

.75 

.75 

11 

549.0 

55.00 

10.02 

549.0 

52.60 

9.58 

4.59 

.75 

.75 

13 

364.0 

35.70 

9.81 

364.0 

34.55 

9.49 

3.  37 

.75 

.75 

17 

800.0 

80.25 

10.03 

600.0 

55.50 

9.25 

8.43 

.75 

.00 

18 

720.0 

71.15 

9.88 

540.0 

49.80 

9.22 

7.16 

.75 

.00 

24 

1,254.0 

122.  80 

9.79 

660.0 

61.90 

9.38 

4.37 

.75 

.75 

27 

570.0 

55.30 

9.70 

380.0 

35.70 

9.39 

3.30 

.75 

.75 

28 

420.0 

40.85 

9.73 

420.0 

40.05 

9.54 

1.99 

.75 

.75 

May 

2 

636.0 

65.05 

10.23 

424.0 

42.00 

9.91 

3.23 

.75 

.75 

3 

558.0 

54.30 

9.73 

372.0 

35.55 

9.56 

1.81 

.75 

.  75 

8 

1,693.0 

158. 15 

9.34 

800.0 

70.95 

8.87 

5.30 

.75 

.  75 

10 

798.0 

77.60 

9.72 

798.0 

73.70 

9.24 

5.19 

.75 

.  7.5 

15 

1,587.0 

161.60 

10.18 

800.0 

76.90 

9.61 

5.93 

.75 

.  75 

17 

1.088.5 

109.  00 

10.01 

800.0 

76.60 

9.57 

4.60 

.75 

.75 

22 

1.223.0 

129.40 

10.58 

800.0 

78.20 

9.77 

8.29 

.75 

.  75 

25 

851.0 

87.00 

10.22 

800.0 

78.80 

9.85 

3.76 

.75 

.  75 

29 

1,315.0 

138.  60 

10.54 

800.0 

80.20 

10.02 

5.29 

.75 

.75 

June 

1 

798.0 

83.50 

10.46 

800.0 

83.10 

10.39 

.67 

.75 

.  75 

2 

799.5 

82.85 

10.36 

800.0 

79.50 

9.94 

4.23 

.75 

.75 

7 

790.5 

79.65 

10.07 

800.0 

76.60 

9.57 

5.22 

.75 

.  75 

9 

800.0 

82.30 

10.29 

800.0 

78.15 

9.77 

5.32 

.75 

.75 

13 

1,090.0 

119.  70 

10.98 

800.0 

80.20 

10.02 

9.58 

.75 

.00 

15 

795.0 

85.50 

10.75 

800.0 

80.70 

10.09 

6.54 

.75 

.75 

16 

800.0 

83.45 

10.  43 

800.0 

78.95 

9.87 

5.67 

.75 

.75 

19 

810.0 

87.60 

10.81 

800.0 

79.65 

9.96 

8.54 

.75 

.00 

21 

798.5 

81.75 

10.24 

800.0 

77.70 

9.71 

5.46 

.75 

.75 

26 

770.0 

80.65 

10.47 

770.0 

75.45 

9.80 

6.84 

.75 

.00 

27 

801.0 

83. 50 

10.42 

800.0 

79.00 

9.88 

5.46 

.75 

.  75 

28 

801.5 

85.90 

10.73 

800.0 

82.00 

10.25 

4.68 

.75 

.75 

July 

3 

1,  234.  0 

122.  75 

9.95 

800.0 

72. 35 

9.04 

10.07 

.75 

.00 

6 

995.0 

102.45 

10.30 

660.0 

66.10 

10.02 

2.79 

.75 

.7.5 

8 

1,068.0 

108. 50 

10.16 

660.0 

62.80 

9.52 

6.72 

.75 

.00 

10 

1,064.5 

107.  30 

10.08 

800.  0 

74.35 

9.29 

8.50 

.75 

.00 

11 

914.0 

93.50 

10.23 

660.0 

63.65 

9.64 

6.12 

.75 

.00 

12 

873.0 

93. 15 

10.67 

800.0 

78.20 

9.77 

9.21 

.75 

.75 

24 

1,195.0 

125.10 

10.47 

600.0 

58.20 

9.70 

7.94 

.75 

.  75 

26 

1,099.0 

118.32 

10.77 

190.0 

19.  32 

0.17 

5.90 

.75 

.00 

Aug. 

29 

294.5 

31.58 

10.72 

290.0 

30.50 

10.52 

1.90 

.75 

.75 

30 

344.0 

35.82 

10.41 

340.0 

34.05 

10.01 

4.00 

.75 

.75 

Sept. 

1 

322.0 

34.10 

10.59 

320.0 

32.  60 

10.19 

3.92 

.75 

.75 

5 

291.5 

31.00 

10.63 

292.0 

29.65 

10.15 

4.73 

.75 

.  75 

6 

276.0 

28.95 

10.49 

275.0 

27.20 

9.89 

6.46 

.75 

.75 

7 

286.5 

31.03 

10.83 

286.5 

29.48 

10.29 

5.24 

.75 

.  75 

8 

292.0 

31.50 

10.79 

292.0 

30.25 

10.36 

4.14 

.75 

.75 

20 

263.0 

29.15 

11.08 

263.0 

27.80 

10.57 

4.82 

.75 

.75 

22 

265.0 

29.20 

11.02 

266.5 

28.05 

10.52 

4.75 

.75 

.75 

25 

748.0 

83.90 

11.22 

250.0 

26.40 

10.56 

6.25 

.75 

.75 

Oct. 

2 

700.5 

79.25 

11.31 

420.0 

45.10 

10.74 

5.31 

.75 

.75 

A  vera 

3 

ge. . 

251.0 

27.75 

11.05 

250.0 

26.25 

10.50 

5.24 

.75 

.75 

10.      7 

9.815 

5.374 

" 



CHKDDAB   CHSE8B    PBOM    PASTBUBIZBD   MH.K. 

It  w;ll  be  noted  thai  every  day  in  the  season  there  waa  a  greater 
a  ield  <»f  cheese  from  the  pasteurized  milk.     Prom  250  to  1  .Too  pounds 
of  milk  were  bandied  in  each  rat.     The  average  yield  of  green  ch< 
from  raw  milk  was  9.815  pounds  ami  from  pasteurized  milk  l> 
pounds  per  hundred  pounds  of  milk. 

The  daily  increase  in  yield  ranged  from  0.6  per  cent  t<>  12  per  rent, 
and  in  50  casea  (72  per  cent    lay  between  •':  and  8  per  cent,  while  the 
average  increase  in  yield  l>y  the  new  pmci^  on  69  day-  was  ~>.:;7  per 
cent.1     On  h")  days  the  same  proportion  <»f  >kim  milk  starter     tl 
fourths  per  <-<-nt     was  uaed  in  both  the  raw  and  the  pasteurized 

milk.      In   the   raw   milk   none   vtaa  used    on    16  days,   and   on  s  days 

l  tu  2\  per  cent  ion  the  average  1.71  per  cent  was  used,  while  in 
every  case  the  pasteurized  milk  received  three-fourths  per  cent 
Btarter.  If  the  use  of  starter  affects  the  yield  of  cheese,  the  average 
yield  from  the  pasteurized  milk  on  in  day-  was  raised  about  three- 
fourths  per  cent,  while  the  average  yield  from  raw  milk  was  i 
on 8  days  about  1.71  pet- cent.  These  two  effects  offset  each  other 
in  the  table,  giving  a  slight  advantage  to  the  yield  from  the  raw  milk, 
so  that  the  final  average  figure  ")..*>7  per  cent  representing  the  aver- 
:ain  in  yield  of  green  cheese  by  the  new  process,  i>  no  higher  and 
possibly  a  trifle  lower  than  it  would  have  heen  if  equal  proportions  of 
Btarter  had  heen  used  in  all 

Among  the  17  cases  in  Table  *J(>  in  which  no  starter  was  used  in  the 
raw-milk  vat.  the  average  gain  in  the  pasteorized-milk  vat.  using 
three-fourths  per  cent  Btarter,  was  7.48  per  cent ;  and  in  B  casea  where 
more  than  three-fourths  per  cent  Btarter  was  uaed  in  the  raw  milk,  the 
average  gain  in  yield  in  the  pasteurized-milk  vat  was  '■'>  per  cent. 
From  thia  it  would  appear  that  the  proportion  of  starter  used  does 
notably  affect  the  yield  of  cheese,  contrary  to  BOme  recent  >tateinent>.2 

;»  B    FOB    SYSTEMATIC    ERRORS    IN    EXPERIMENTS   ON"    YIELD   OF   CHI  I 

The  presence  of  systematic  errors  was  carefully  guarded  against  in 
the  daily  work  on  the  yield  of  cheese.  Before  dividing  the  milk  from 
the  receiving  vat  for  use  in  the  two  make  vats,  the  milk  was  first 
thoroughly  stirred  for  i  to  10  minutes,  as  already  stated,  and  the  Btir- 
ring  was  continued  while  the  milk  was  running  out.  The  portion  of 
milk  drawn  out  first  was  commonly  used  for  making  the  raw-milk 
cheese,  but  sometime-,  as  on  March  8,  :•.  in.  17.  lM.  22,  and  April  7, 
11.  17.  18,  and  May  10,  the  portion  drawn  first  was  used  for  making 
the  past  urized-milk  cheese.     The  average  gain  in  yield  through  pas- 

i  Both  the  medial)  and  the  mode  lie  l>etw- .  r  i-ent.     The  mode  is  the  class  which  000O1 

nqueney;  U  the  magnitude  at  the  middle  of  the  series  from  larger 

B.DftVBOp  Principles  of  Breeding."  by  E.  Daven- 

of cheese  making.     New  York, 


INCREASED    HELD   OF   CHEESE   OBTAINED.  57 

teuiization  on  these  1 1  days  was  5.15  per  cent,  so  nearly  equal  to  the 
general  average  of  5.37  per  cent  (sec  Table  20)  as  to  indicate  thai  the 
gain  in  yield  is  not  due  to  any  difference  in  composition  of  the  milk 

when  divided  into  two  lots.  Carefully  tested  thermometers  and  the 
same  pair  of  curd  knives  were  used  in  every  vat. 

Usually  the  vat  of  pasteurized  milk  was  set  first  with  rennet,  and 
the  vat  of  raw  milk  5  minutes  later.  The  two  vats  were  placed  near 
each  other,  and  conditions  were  such  that  one  operator  could  stir 
them  both  at  once,  if  desired.  On  11  days,  April  IS,  24,  27,  May  S, 
10,  15,  17,  August  29,  30,  September  1,  and  October  2,  the  rennet  was 
added  to  the  raw  milk  first,  and  to  the  pasteurized  milk  5  minutes 
later.  The  average  gain  in  yield  on  the  11  days  was  4.63  per  cent, 
indicating  that  the  order  of  setting  the  vats  had  nothing  to  do  with 
the  gain  in  }rield. 

In  order  to  ascertain  what  per  cent  of  unavoidable  error  enters  into 
the  measurement  of  yield  of  cheese,  a  special  experiment  wTas  performed 
on  34  days.  Each  day,  with  all  of  the  usual  precautions,  two  lots 
of  milk  drawn  from  the  receiving  vat  were  run  through  the  pasteurizer, 
one  after  the  other,  and  made  up  into  cheese  in  separate  vats  marked 
(C)  and  (D)  standing  near  each  other,  and  handled  by  the  same  oper- 
ator (Mr.  Bruhn).  The  vats  were  heated  and  set  exactly  5  minutes 
apart  by  the  wTatch,  and  the  time  schedule  for  each  vat  was  strictly 
followed  in  every  detail.  The  same  curd  knives  and  thermometer 
were  used  in  both  vats. 

The  pasteurizer  and  cooler  are  ahvays  rinsed  with  hot  water  at  the 
beginning  of  the  first  run,  but  are  wet  with  adhering  milk  at  the  close 
of  the  run  just  before  beginning  the  second  run.  Thus  the  actual 
weight  of  milk  in  the  first  vat  might  be  slightly  less  than  it  should  be. 
To  avoid  this  source  of  error,  the  pasteurizer  and  cooler  were  allowed 
to  drain  each  time  into  the  vat  for  several  minutes  (until  the  stream 
of  milk  broke  into  single  drops),  and  then  the  metal  surfaces  were 
carefully  rinsed  with  two  measured  portions  of  clean  water.  Thus 
the  surfaces  of  the  pasteurizer  and  cooler  wrere  wet  with  water  at  the 
beginning  of  the  second  run  as  wTeft  as  the  first.  The  milk  content 
of  the  rinsings  (see  Table  21)  was  found  to  be  very  small  and  uniform, 
amounting  to  about  0.8  of  a  pound  of  milk  each  time,  which  if  it  were 
all  lost  from  one  vat  but  not  the  other  would  cause  a  difference  of 
yield  of  cheese  from  a  500-pound  lot  of  milk  (as  in  Table  22)  of 
about  0.16  per  cent.  In  order  to  avoid  this  source  of  error  entirely, 
the  rinsings  from  both  runs  were  either  thrown  away,  as  on  the  first 
15  days  listed  in  Table  22,  or  the  rinsings  after  each  run  were  added 
to  the  respective  vats,  as  on  the  last  19  days. 


58 


OHEDDAB   CHEESE    FROM    PA8TEUBIZED    MH.K. 
Tabu   2]      Milk  content  of  rii  and  cooler. 


at 

.  hi  of 

••  In 

rinsings. 

-•it  of 

milk  In 
tngfl 

1911. 

Pmt/mia, 

Pounds. 

Pounds. 

The  yield  of  cheese  obtained  in  duplicate  vats  thus  handled  was 
never  exactly  equal  and  varied  on  the  average  for  33  day-  by  0.585 
per  cent  of  the  weight  of  the  cheese,  as  shown  in  Table  22.  The  milk 
in  Vat  C  was  drawn  first  from  the  receiving  vat,  and  was  pasteur- 
ized and  set  first  in  all  cases  except  where  otherwise  noted. 

Tabi  i.  22.      Variation  m  yield  of  cheese  from  duplicate  vats  of  pasteurized  milk. 


Ratio  of 

Vat  I). 

Dtflar 
enee  m 

Weigh! 

Weight 

milk 

Weight 

yield  of 
the  two 

of  milk 

of  green 

per  cut. 

of  milk 

J*T  CWt. 

of  milk. 

cheese. 

of  milk. 

Vat    Vat 

1911 

1'nunds. 

Pounds. 

Pou  nds. 

C.    D. 

Pou  nds. 

Pounds. 

Pounds. 

Per  cent. 

Mar.  23 

430.0 

1      1 

42.55 

0.11 

390.0 

9.949 

1      1 

390.0 

39.10 

iaoo6 

.77 

27 

36.10 

1      3 

1,125.0 

109.20 

• 

a 

10.  457 

1      2J 

10. 537 

59. 10 

10. 102 

i;    i 

390.0 

39.45 

10.115 

.13 

30 

50.10 

10.121 

ii    l 

330.0 

33.50 

10.151 

.30 

31 

540.0 

10.038 

360.0 

36.15 

10.042 

.04 

Apr.    4 

585.  0 

ttO.  50 

10.  342 

ii    l 

390.0 

10.307 

6 

54.  15 

10.  140 

lj   l 

37. 35 

•3.46 

10 

1,080.0 

106.30 

9  842 

3       1 

36a  0 

35.65 

.62 

12 

555.0 

10.036 

li     1 

370.0 

37.60 

10. 162 

14 

38a  0 

38.  10 

10.  026 

1       1 

- 

10.105 

1" 

400.0 

40.30 

10.075 

1       1 

4O0.0 

10.  150 

.74 

- 

370.  0 

1       11 

55..0 

55.40 

.50 

21 

a 

87.00 

1       U 

570.0 

55.45 

4  21  Ml 

41.00 

- 

.25 

26 

3m  o 

36.  20 

1       U, 

555.0 

54.35 

.09 

May    4 

42.  lo 

10.024 

1       1 

420.0 

12    " 

10.119 

.95 

5 

51.40 

n   i 

354.0 

D 

4a  65 

i     n 

612.0 

11 

410.0 

41.50 

10.  122 

l     i 

410.0 

41.  Ml 

In  195 

12 

795.0 

i     i 

laooo 

1.59 

800.0 

10.037 

i     i 

Boao 

In  (161 

.44 

is 

10.633 

l     i 

10.450 

1.75 

600.0 

W.387 

i     i 

10.325 

.41 

23 

i     i 

10.625 

.39 

24 

612.25 

10.510 

i     l 

612.25 

ln.Ml 

1.24 

30 

600.0 

61.30 

10.217 

i     l 

eoao 

in.  125 

.91 

600.0 

10.350 

i     i 

600.0 

10.353 

.03 

June  6 

Hi.  146 

i     l 

.91 

B 

l     l 

10.308 

.49 

ii 

600.  0 

i     l 

62.  15 

10.358 

.21 

17 

62.71 

in  160 

i     i 

63.  1 1 

■Jii 

600.0 

60.30 

111    (Ml 

i     i 

..(HI    II 

60.90 

10.150 

.99 

- 

10.105 

536.37 

10. 149 

'.5S5 

1  The  recall  foe  Apr.  6  Is  omitted  In  computing  i  «  of  abnormal  conditions. 

Among  the  34  days'  results  obtained  during  the  season,  as  shown 
ible  22,  the  difference  in  yield  between  duplicate  vats  exceeded 

per  cent   in  only  one  case.     On  this  day  there  was  unusual 
difficulty  in  the  work  because  ^(  unexpected  failure  of  the  supply  of 


DISCUSSION    OF    \\i;i\TKi.\    IN    HELD.  59 

water  for  cooling,  and,  although  the  direct  cause  of  the  exceptionally 
high  figure  (3.46  per  cent)  can  not  be  directly  traced,  i1  -reins  likely 
that  sonic  gross  error  occurred,  which  was  avoided  on  the  other  days. 
Therefore  this  figure  (U)v  April  6)  is  omitted  from  the  general  average. 

On  28  days  (82  per  cent  of  all  cases)  the  variation  in  yield  between 
duplicate  vats  lay  below  1  per  cent  and  on  33  days  (omitting  April  (i)  it 
averaged  0.584  per  cent.  For  present  purposes,  therefore,  it  may  be 
considered  thai  the  figure  5.37  per  cent,  from  Table  20,  representing  the 
average  increased  yield  of  green  cheese  obtained  through  pasteuriza- 
tion, is  correct  within  0.58  per  cent,  or  about  one-ninth  of  its  value. 

The  yield  of  cheese  from  pasteurized  milk  is  thus  capable  of  meas- 
urement with  an  average  difference  between  duplicate  determina- 
tions of  0.6  per  cent  of  the  amount  determined.  This  degree  of 
accuracy  in  manipulation  is  comparable  with  that  attained  in  many 
analytical  chemical  processes,  in  which  a  limit  of  1  per  cent  of  the 
amount  determined  is  commonly  set  as  the  maximum  allowable 
difference  between  duplicates. 

The  principal  cause  for  the  difference  of  0.60  per  cent  in  the  yield  in 
making  duplicate  vats  of  cheese  does  not  lie  in  the  weighing  of  the 
milk  or  cheese,  because  with  the  scales  employed  both  the  milk  used 
and  the  cheese  obtained  therefrom  could  be  weighed  with  an  error 
of  not  over  0.10  per  cent.  The  per  cent  of  difference  in  yield  was  not 
reduced  when  the  weight  of  milk  handled  was  increased.  It  appears 
likely,  therefore,  that  there  are  small  unavoidable  differences  caused 
by  the  size  of  the  cubes  or  in  the  manipulation  of  the  milk  and  curd 
which  cause  an  average  difference  in  yield  of  from  0.50  to  0.60  per 
cent  between  duplicate  vats. 

An  effort  was  made  so  far  as  time  permitted  to  determine  wThether 
any  one  of  several  causes  was  regularly  or  chiefly  responsible  for  this 
average  difference  in  the  yield.  The  stirring  of  the  vats  was  done 
by  hand  in  all  cases  where  the  weight  of  milk  in  a  vat  was  less  than 
400  pounds.  For  experiments  with  400  to  800  pounds  of  milk  in  a 
vat  a  pair  of  vats  of  800  pounds  capacity  wras  used.  These  were 
stirred  with  a  pair  of  wrooden  rakes,  exactly  alike  in  shape  and  size. 
Larger  quantities  of  milk  than  800  pounds  were  always  handled  in  a 
vat  of  2,400  pounds  capacity  in  which  a  two-bladed  rotating  and 
oscillating  agitator  was  used  instead  of  the  rake.  The  difference 
in  yield  between  duplicate  vats  could  not  be  traced  to  the  methods 
of  stirring.  Thus,  on  March  27,  the  agitator-stirred  vat  (D)  gave 
0.83  per  cent  greater  yield  than  the  hand-stirred  vat  (C),  but  on 
April  10  the  hand-stirred  vat  (D)  gave  0.62  per  cent  greater  yield 
than  the  agitator-stirred  vat  (C).  The  average  difference  on  12 
days  in  yield  between  duplicate  rake-stirred  vats  was  0.70  per  cent, 
and  the  average  difference  in  yield  between  duplicate  hand-stirred 
vats  on  19  days  was  0.52  per  cent.  The  differences  varied  slightly 
whatever  method  of  stirring  was  employed. 


60 


("ll  l  M>\l:    till  1-1.    I  ROM     PAS!  EURIZED    MII.K. 


ain,  handling  different  amounts  of  milk  did  not  appear  to  affect 
the  yield  in  duplicate  \ais.  On  L2  days,  using  one  and  one-half  to 
three  times  as  much  milk  in  one  \ ra1  as  in  the  other,  the  average  differ- 
ence in  yield  was  0.40  per  cent,  which  is  a  little  Bmaller  than  the 
average  of  the  other  days,  showing  thai  the  quantity  of  milk  handled 

h\    this  method  does  not   affect   the  yield.      Since  the  same  results  are 

obtained  in  a  small  \ai  with  .17.")  pounds  of  milk  as  in  a  large  one 
with  1,125  pounds  of  milk,  it  is  believed  that  the  general  result^  of 
this  investigation  are  applicable  to  the  Largest  sized  vats  of  milk  used 
m  factories. 

BHRINKAOl     BEFORE    PARAFFINING,    LND  YIELD  Ol     PARAFFINED  CHEESE. 

Since  there  is  always  some  loss  in  weight  of  cheese  previous  to 
paraffining,  it   is  of  interest   to  compare  the  shrinkage  of  ordinary 

cheese   with    that    of   new -process  cheese,    and   to   determine   whether 

there  is  an  increased  yield  of  pasteurized-milk  cheese  when  paraffined 

Corresponding    to    the    increased    yield    observed    in    the    same    c! 
when  green.      This  can  he  done  readily  from  Table  23,  which     shows 
the  average  results  for  the  season  and  also  the  range  of  daily  variation. 

Table  23.     Comparison  of  old  and  new  process  che*  hrinkagt  be/on  paraffining 

anil  yii  Id  of  paraffined  <  i  ■ 


Shrinkage  per  loo 

pounds 

of  green 

Yield 

per    100 

A  ge 

cheese 

hi'  fore 

pounds  of  in 

(lain  in 

when 

paraffining. 

yield 

made. 

jiar- 
alline«l. 

by  new 

process. 

Pasteur- 
ized. 

Raw. 

Pasteur- 
ized. 

MM. 

Dat/s. 

Pounds. 

Pounds. 

Pound*. 

1 '<>u  nds. 

Per  cent. 

Peb.  23 

19 

6.  '.'2 

5.  23 

9.30 

24 

1^ 

5.98 

9.60 

9.  14 

27 

15 

4.67 

9.  Is 

<  |  i 

28 

14 

7).  23 

4.  7,7 

'.'  74 

9.  14 

Mar.      1 

13 

4.ss 

1*.  36 

2   21 

•j 

12 

6.26 

4.  36 

9.  49 

4.44) 

ii 

17) 

6.71 

«.»71 

'.'.  4s 

2.  4:< 

7 

11 

4.  ).i 

111 

- 

10 

1    s, 

9 

'.' 

4.S2 

9.35 

3.53 

10 

■A.  35 

•'.  17 

13 

12 

:,.us 

4.2s 

14 

11 

5. 13 

4.26 

10.26 

9.50 

us 

10 

3.96 

;i.  73 

9.  7s 

9.50 

16 

it 

4.  22 

3.61 

16.25 

10.04 

17 

B 

3.  27 

10.03 

•-'(i 

12 

4.;<7 

9.  1 1 

:,  16 

L'l 

11 

1    12 

23 

10 

4.72 

9.  19 

Apr.     5 

10 

4.  36 

9.  82 

7 

B 

4.  10 

8, 85 

9.20 

)     Ml 

11 

10 

4.66 

9.51 

9.  14 

4.06 

a 

B 

4.06 

'.i.  1 1 

2.  i  3 

17 

12 

6.  1 1 

4.23 

7   16 

Is 

11 

1    v.", 

4.42 

9.40 

8.81 

21 

12 

6.06 

4.11 

9.  M) 

27 

3.  -  1 

9.  32 

28 

B 

1.72 

Mr,        2 

11 

:<.  93 

I 

10 

•1   us 

9.31 

«».  17 

1.61 

B 

13 

i  66 

8.01 

in 

U 

i  I't 

:<.  73 

9.  32 

i:. 

12 

i  1  i 

4.36 

9.71 

9.  I'i 

17 

ID 

•*.  4<> 

'.I.  I'i 

22 

12 

4.71 

in. us 

7.7,7 

28 

11 

4.71 

9.74 

u 

4.72 

4..!7 

in. in 

4.e.» 

COMPARISON    OF    S1IK1NK  \i;K    IJY    OLD    AND    N  E  \\     PROCESSES.        01 


Table  23. — Companion  <>/ <>l<l  <t»<!  new  process  cheese  as  i<>  shrinkage  before  paraffining 
ana  yield  of  paraffined  cheese    Continued. 


Shrinkage  pit  kid 

pounds 

of  green 

y  [eld 

por    100 

Ago 

oheese 

berore 

pounds  of  milk. 

1  i;iiii  in 

Date 

when 

paraffining. 

yield 

made. 

paraf- 
fined. 

by  new 

Pasteur- 
ized. 

Raw. 

Pasteur- 
ized. 

Ra  a 

1911. 

Days. 

Pounds. 

Pounds. 

Pounds. 

I'tni  mis. 

Per  ci  nt. 

June     1 

10 

3.92 

3.67 

10.05 

HUH 

n.  id 

2 

9 

4.22 

3.92 

9.93 

'i..., 

3.  98 

7 

7 

4.21 

3.  66 

9.66 

9.  22 

4.77 

9 

8 

3.80 

3.58 

9.90 

!i.  42 

5.09 

13 

10 

5.26 

4.74 

10.40 

9.55 

s.  Ill) 

15 

8 

4.49 

3.82 

10.18 

9.70 

4.  it.", 

16 

7 

4.43 

3.64 

9.97 

9.51 

4.84 

19 

12 

4.85 

4.27 

10.29 

9.53 

7.97 

21 

10 

4.46 

4.18 

9.78 

9.31 

5.05 

26 

12 

4.53 

4.17 

10.00 

9.40 

6. 38 

27 

11 

4.19 

3.80 

9.99 

9.50 

5.16 

28 

10 

4.02 

3.41 

10.30 

9.90 

4.04 

July      3 

14 

4.56 

3.91 

9.49 

8.69 

9.21 

6 

11 

4.20 

4.01 

9.86 

9.61 

2.  60 

8 

9 

3.  64 

3.42 

9.79 

9.19 

6.  .53 

10 

10 

4.80 

4.64 

9.  60 

8.86 

8.  35 

11 

11 

4.46 

4.01 

9.77 

9.26 

5.51 

12 

10 

4.54 

3.6;": 

10.19 

9.42 

8.17 

Aug.  29 

11 

4.99 

6.07 

10.18 

9.88 

3.14 

30 

10 

4.22 

4.05 

9.97 

9.61 

3.75 

Sept.    1 

8 

4^14 

4.14 

10.15 

9.77 

3.89 

5 

13 

4.35 

4.05 

10.17 

9.74 

4.42 

6 

12 

3.82 

3.49 

10.09 

9.54 

5.65 

7 

11 

3.49 

2.99 

10.45 

9.98 

4.71 

8 

10 

3.17 

2.81 

10.45 

10.07 

3.77 

20 

10 

3.80 

3.41 

10.66 

10.21 

4.41 

22 

8 

3.43 

3.21 

10.64 

10.19 

4.42 

25 
Average.. 

16 

6.49 

5.87 

10.49 

9.94 

5.53 

4.546 

4.078 

9.833 

9.3S8 

4.761 

In  practically  every  case  in  Table  23  the  pasteurized-milk  cheese 
showed  a  greater  shrinkage  than  the  raw-milk  chees e  during  the  period 
before  paraffining,  which  was  7  to  19  days.  The  average  shrinkage 
of  raw-milk  cheese  before  paraffining,  for  all  65  cases,  was  4.08 
pounds  per  hundred  of  green  cheese,  and  for  the  pasteurized-milk 
cheese  it  was  4.55  pounds  per  hundred,  nearly  one-eighth  greater 
than  the  raw.  This  excess  shrinkage  is  observed  whether  the  cheese 
was  paraffined  at  7  or  14  days,  as  is  shown  in  the  following  table, 
which  is  a  summary  of  Table  23. 

Table  24. — Shrinkage  of  cheese  when  paraffined  at  different  ages  (summary  of  Table  28). 


Average  shrinkage  in 

weight      per     100 

Age  when 
paraffined. 

Cases  av- 
eraged. 

pounds  green  cheese. 

Excess  in  pasteurized. 

Pasteur- 
ized. 

Raw. 

Per  cent  of 

Days. 

Number. 

Pounds. 

Pounds. 

Pounds. 

raw. 

7  to    8 

11 

3.  9.5 

3.56 

0.39 

11 

9 

5 

4.31 

3.88 

.43 

11 

10 

16 

4.35 

3.83 

.52 

13 

11 

12 

4.52 

4.10 

.42 

11 

12 

10 

4.84 

4.17 

.67 

16 

13  to  19 

11 

5.29 

4.78 

.51 

11 

62 


<   II  EDDAR    I   ll  EESE    1  ROM     PAS!  EURIZED    MILK. 


On  account  of  this  excess  shrinkage  before  paraffining,  amounting 
to  about  one-half  |><»iin<l  per  hundred  pounds  of  cheese,  the  average 
increased  yield  of  5.37  pounds  per  hundred  of  milk  observed  in  t he 
pasteurized  cheese  when  green  (Table  20)  was  reduced  to  4.76  pounds 

e  Table  23    bj  the  time  the  cheese  was  paraffined. 

BHRINKAOI    \M'    FIELD  OF  CI  BSD   «  ll  I  i  SI 

The  further  shrinkage  and  yield  <>f  cheese  after  paraffining  was 
studied:  (1)  With  cheese  cured  at  Madison,  Wis.,  .-it  a  temperature 
t<»  7"»  :  (2)  with  cheese  cured  al  New  Orleans,  La.,  and  weighed 
both  at  New  Orleans1  and  Madison;  (3  with  cheese  cured  at  New 
Orleans  or  at  Columbus,  Ga.,  and  weighed  both  at  Chicago  and  at 
Madison;  I  \>  with  cheese  cured  in  a  warm  room  at  Madison;  and  (5) 
with  cheese  put  in  cold  Btorage  at  :;  1  K.  at  Waterloo.  Wis.,  at  differ- 
ent ages  after  paraffining.  So  far  a-  possible  duplicate  cheeses  from 
the  same  days'  make  were  cured  in  the  different  ways  stated. 

These  different  methods  of  curing  were  chosen  for  study  as  repre- 
senting (1)  curing  conditions  at  Wisconsin  factories;  (2),  (3),  and  (!) 
condition.  t«»  which  annually  large  amounts  of  cheese  arc  subjected 
when  shipped  south  for  sale;  and  (">)  when  cured  in  cold  storage  as 
Commonly  practiced  by  dealer-. 

The  shipments  to  New  Orleans  wore  sent  on  four  date-  between 
April  29  and  July  24,  1911.     Each  shipment  consisted  of  9  to  25 
pasteurized-milk  cheeses,  and  an  equal  Dumber  of  raw-milk  eh' 
for  comparison.     In  order  that  the  cheese  stored  might  he  a-  repre- 
sentative as  possible,  each  pair  represented  a  different  day's  make. 

l-'->r  each  lot  of  cheese  shipped  away  from  Madison  for  storage,  a 
duplicate  lot  from  the  same  days'  make  was  kept  at  Madison.  The 
method  of  designating  these  different  l<>t>  of  cheese  is  Bhown  in 
Table  25: 

Table  25. — Rej  mh<  rs  to  diffen  >rf  lots  of  cheese  stored  in  l^n . 


Data  made. 

CI  .  ■ 

Cured  at 
Madison. 

Cured  at 
New  Or- 
leans. 

Ci:n'<l  at 
New  <  >r- 

leans  and 
Columbus, 

(la. 

Cured  in 
warm  room 
at  Madison 

Cured  at 
Moo, 

Feb.  23  i"  Apr.  if,.... 

Api                        17 

,M:i\  23  to  June  16.. . . 
Jane  19  to  July  12. ... 
July  n  i"  Aug.  21.... 

ri  to  l'ii: 
211  1 
230  ' 
248  to  263 

!  \ 

u 

3A 

)  \ 

■  \ 

IB     

2B 

3B 

415 

3C 

4C  . 

41) 



Tn  addition  to  weighing  each  cheese  separately  they  were  also 
weighed  in  lots  of  five,  and  the  close  agreement  of  the  weight  of  a  lot 

details  of  the  work  at  New  Orleans  connected  with  the  storage,  weighing,  and  shipping  of  the 

Mr.    W '.  J.    Bleacher,  junior  dairyman  of  the  Dairy  Division, 

Bureau  of  Animal  industry.    Thanhs  are  duo  to  Mr.  Blaaohar  for  his  vary  careful  attention  to  this  work. 


CUEING    VARIOUS    l.K  N  <  i'l  1 1  S    t>l      I  I  M 


63 


of  five  with  the  sum  of  the  five  separate  weights  proved  the  accuracy 
of  the  weighing.  This  general  method  of  double  weighing  was 
followed  in  obtaining  all  the  weights  of  cheese  in  the  I  1  lots. 

The  tabulated  results  show  the  shrinkage  of  the  different  lots  and 
the  yield  of  green,  paraffined,  and  cured  cheese  per  hundred  pounds 
of  milk.  In  addition  to  tin4  average  results  for  each  lot  of  cheese, 
the  individual  variations  in  shrinkage  and  yield  of  the  single  chei 
are  shown,  from  which  the  extent  of  daily  variations  from  the  general 
average  figures  can  be  studied  by  anyone  interested. 

Cheese  cured  at  Madison  (lots  1A  to  5 A). — Fifty-two  pairs  of  cheese 
cured  at  60°  to  70°  wrere  weighed  one  or  more  times  (92  times  in  all)  at 
different  ages,  from  21  to  117  days  after  paraffining.  In  every  case 
there  was  a  gain  in  yield  of  pasteurized  cheese  over  raw  cheese.  The 
gain  averaged  4.59  per  cent  among  10  pairs  of  cheese  cured  20  to  30 
days,  4.58  per  cent  among  37  pairs  of  cheese  cured  30  to  60  days, 
4.38  per  cent  among  28  pairs  of  cheese  cured  60  to  90  days,  and  3.58 
per  cent  among  17  pairs  of  cheese  cured  90  to  117  days.  On  the 
average  of  all  cases  the  gain  in  yield  of  pasteurized  over  raw  was 
4.22  per  cent  of  the  weight  of  the  cheese. 

Table  26. — Comparison  of  yield  of  raw  and  pasfeurized-mtlk  cheese  after  curing  for 
various  lengths  of  time  at  Madison,  Wis. 


Weight 

of    cured 

Time 

cheese 

per    100 

Date 
made. 

cured 
alter 

pounds 

of  milk. 

Gain  by  pasteur- 
ization. 

paraffin- 

ing. 

Pasteur- 
ized. 

Raw. 

1911. 

Days. 

Pounds. 

Pounds. 

Pounds. 

Per  cent. 

Apr.   24 

21 

9.27 

8.96 

0.31 

3.46 

Mar.   20 

26 

9.52 

9.06 

.46 

5.08 

21 

26 

9.40 

8.94 

.46 

5.15 

22 

26 

9.37 

9.12 

.25 

2.74 

20 

33 

9.47 

8.99 

.48 

5.34 

17 

32 

9.87 

9.63 

.24 

2.49 

16 

32 

10.02 

9.96 

.06 

.60 

15 

32 

9.68 

9.38 

.30 

3.20 

14 

32 

10.03 

9.34 

.69 

7.38 

13 

32 

9.72 

8.80 

.92 

10.46 

2 

42 

9.53 

9.36 

.17 

1.81 

7 

42 

9.57 

9.49 

.08 

.84 

8 

42 

9.61 

9.51 

.10 

1.05 

9 

42 

9.55 

9.29 

.26 

2.80 

10 

42 

9.62 

9.09 

.53 

5.83 

Apr.  17 

42 

9.30 

8.73 

.57 

6.54 

18 

42 

9.13 

8.64 

.49 

5.67 

May  15 

44 

9.43 

8.89 

.54 

6.07 

17 

44 

9.15 

8.85 

.30 

3.39 

June  13 

44 

9.86 

8.94 

.92 

10.29 

15 

44 

9.70 

9.30 

.40 

4.30 

16 

44 

9.64 

9.04 

.60 

6.64 

Feb.   23 

45 

9.12 

8.63 

.49 

5.67 

24 

45 

9.26 

8.93 

.33 

3.69 

27 

45 

9.51 

9.00 

.51 

5.67 

28 

45 

9.49 

8.99 

.50 

5.56 

Mar.     1 

45 

9.57 

9.08 

.49 

5.39 

2 

45 

9.21 

8.94 

.27 

3.02 

Apr.   11 

50 

9.29 

8.98 

.31 

3.45 

13 

50 

9.06 

8.86 

.20 

2.26 

May    10 

50 

8.95 

8.51 

.44 

5.17 

June    7 

50 

9.19 

8.79 

.40 

4.55 

9 

50 

9.41 

8.58 

.83 

9.67 

64 


CHEDDAR    CHEESE    FROM     PASTEURIZED    MII.K. 


Tabu    26.— H  td-milk  cfo  canny  fur 

1    otinued. 


Time 

cured 

pounds  of  milk. 

by 

.  -n. 

• 

■ 

191 1. 

I'i  r  a  nt. 

Jul. 

51 

61 

.14 

- 

JllIU'       1 

•  .10 

1.06 

Mi 

\: 

km 

Ma 

58 

3 

.if, 

1.84 

Apr.      7 

.47 

62 

9.40 

v   71 

ft] 

9.16 

.  17 

28 

•  -1 

19 

21 

0.  If, 

.44 

ATM 

65 

.15 

1.70 

65 

8.10 

.68 

24 

9.01 

.  33 

Mar.   10 

'X  10 

24 

21 

«.'.  1.') 

.  18 

20 

9.15 

B.74 

.41 

Apr.    17 

is 

72 

8.81 

.47 

Mar.    17 

74 

'.i.  4.: 

.1.") 

lf> 

74 

.17 

1.7s 

1.5 

74 

3.09 

14 

74 

7.01 

14 

74 

-  " 

.84 

Apr.    13 

.is 

11 

VI) 

.V74 

.24 

7 

.41 

4.72 

5 

.4.-> 

'      ' 

Mar.     9 

B4 

8 

84 

9.  40 

9.09 

.:,1 

3.41 

7 

B4 

9.13 

.  26 

•J.  V, 

3 

84 

9.24 

2.44 

- 

87 

1 

-7 

.12 

Feb     28 

w 

9.25 

v71 

27 

S7 

B.78 

^7 

. 

-     3 

Mar.   20 

- 

3.71 

21 

- 

V44 

.:.i 

6.04 

22 

8.91 

17 

104 

.12 

16 

104 

9.61 

.if. 

1.71 

15 

104 

9  12 

14 

104 

'.'.41 

13 

104 

'.'.14 

• 

- 

114 

3.44 

8 

114 

0.  1  4 

V        XV 

- 

! 

7 

'      114 

9.14 

.21 

3 

114 

9.06 

.21 

2 

117 

S  - 

8.51 

.29 

:;.4l 

1 

117 

.11 

1.2S 

Feb.   28 

117 

9.  l.' 

- 

.40 

117 

o.  16 

.46 

24 

117 

.17 

1   "7 

Avt  ■ 

8.907 

.38 

4.22 

Cl<<<s,  stay,,]  at  New  Orleans  (J<>ts   IB  to  J[B).     Fifty-four  days1 
make  represented  by  •">  l  raw  mid  54  pasteurized-milk  cheeses  were 
shipped  to  New  Orleans  in  four  lots  at  different  times  during  the 
n.     Tli.  ihowed  an  increased  yield  for. the  new-process 

cheese  compared   with   the  old.   in    every   case.     The   average 

figures  f<»r  each  l<>t  are  given  in  Table  27, 


CUBING    VARIOUS   LENGTHS   OB1   TIME. 


05 


Table  27. — Average  yield  per  100  pound*  of  milk  of  raw  and  pasteurized-milk 

cured  a!  YU. 


Method. 

Num- 
ber of 
days' 

make. 

Yield  of  cheese 

per  100  pounds  of  milk. 

Lot 

Green. 

Paraf- 
fined. 

Ship- 
ped 

to  New 

Or- 
leans. 

Re- 
al New 

Or- 
leans. 

Stored 

one 

month. 

two 
months. 

Re- 
ceived 

at 
Madi- 
son. 

f  Pasteurized 

25 
25 

Pounds. 
11).  lvi 
9. 67 

Pounds. 
9.26 

Pounds. 
9.55 
9.16 

Pounds. 
9.52 

9.14 

Pounds. 
8.36 

Pounds. 

7.85 

Pounds. 
8.31 

Haw 

7.78 

IB 

Gain,  pounds 

.52 
5.37 

.43 

4.64 

.39 

4.25 

.  38 

4.16 

.49 
5.86 

.53 
6.75 

.53 

Gain,  per  cent 

6.81 

9 
9 

9.  S3 
9.45 

9.40 
9.08 

9.37 
9.05 

9.26 

8.97 

8.48 
8.12 

8.40 

Raw 

8.01 

2B 

Gain,  pounds 

.38 
4  02 

.32 
3.52 

.32 
3.54 

.29 
3.23 

.36 
4.43 



.39 

4.87 

f  Pasteurized 

10 
10 

10.47 
9.93 

9.99 
9.54 

9.92 
9.47 

9.77 
9.34 

9.29  1 

8.69    

9.17 

Raw 

8.55 

3B 

Gain,  pounds 

.54 
5.44 

.45 

4.72 

.45 

4.75 

.43 
4.60 

.60    

0.90    

.62 

Gain,  per  cent 

7.25 

f  Pasteurized 

10 

10 

10. 38 
9.G9 

9.92 
9.31 

9.83 
9.24 

9.78 
9.19 

8.94  : 

8.71 

Raw 

8.28 

8.14 

4B 

Gain,  pounds 

.69 
7.12 

.61 

6.55 

.59 
6.38 

.59 
6.42 

.66 
7.97 

.57 

Gain,  per  cent 

7.00 

(Pasteurized 

54 
54 

10.  22 
9.68 

9.74 
9.29 

9.64 
9.21 

9.57 
9. 16 

8.89 
8.37 

8.56 

Raw 

8.03 

1-4  B 

Gain,  pounds 

.54 
5.58 

.45 

4.84 

.43 

4.<J7 

.41 

4.47 

.52 

6.21 

.53 

Gain,  per  cent 

6.60 

Among  the  four  lots  in  Table  27,  and  in  the  summary  at  the 
bottom  of  the  table,  it  will  be  seen  that  the  percentage  of  gain  in 
yield  of  pasteurized  cheese  over  raw  fell  off  slowly  as  the  green 
cheeses  were  paraffined  and  shipped,  on  the  average  from  5.58  to  4.47 
per  cent.  After  these  cheeses  had  been  in  storage  at  New  Orleans 
for  one  month,  the  raw-milk  cheeses  were  found  to  have  shrunk 
more  than  the  pasteurized  in  the  majority  of  cases,  raising  the  per- 
centage of  gain  in  average  yield  of  pasteurized  cheese  to  6.21  per 
cent.  This  was  also  observed  in  lot  IB  after  the  second  month  of 
storage,  and  is  confirmed  both  by  the  weights  taken  in  New  Orleans 
by  Mr.  Bleecker  and  by  the  weights  taken  at  Madison.  It  was 
expected  that  the  pasteurized-milk  cheese,  containing  slightly  more 
moisture  than  the  raw-milk  cheese,  would  lose  more  in  weight  than 
the  latter  when  stored  at  high  temperatures.  It  was  surprising  to 
find  that  the  reverse  is  true  in  most  cases. 

The  mean  daily  temperature  at  New  Orleans,  as  reported  by  the 
United  States  Weather  Bureau,  varied  from  71,  the  average  for  April, 
to  83,  the  average  for  June.  It  is  likely  that  the  temperature  of  the 
cheese  in  the  warehouse  was  somewhat  higher  than  the  average 
figures  given  above,  because  the  warehouse,  although  well  ventilated, 
79994°— Bull.  165—13 5 


66 


CHEDDAB    CHEESE    FROM    PASTEURIZED    MILK. 


i    i       rily  open  mora  or  Less  during  the  hot  days  and  cl< 
during  the  cool  nights. 

cured  at  .V  a/nd  at  Columbu  lots  SG  and 

Forty  cheeses,   including  20   pasteurized   and   20   raw,  were 

shipped  in  two  ship]  >r  Btorage  in  the  South  through  a  firm1 

ofchi  lera  in  Chicago,  who  weighed  the  cheese,  both  before  and 

after  Btorage  for  one  month. 

In  the  first    shipment    l    cheese,  No.   243  -    Lost  in  transit, 

and  iji    the   second    shipment,  2  ch<  254   1    and    254C1, 

were  damaged  so  thai  their  weights  arc  not  included  in  the  following 
summary.     Jn  the  first  shipment,  according  to  the  Chicago  weights, 
9  pasteurized-milk    cheeses   weighed    172J    pounds    before 
and  162]  pounds  afterwards.     The  loss,  10J  pounds,  is  5.94  percent 
of  the  original  weight.     In  the  dpment  K)  raw-milk  ch( 

weighed   189J  pounds  before  shipment   and   175  pounds  afterwards. 
The  Loss  here.  14J  pounds,  is  7.53  per  rent  of  the  original  weight. 

Jii   the  second   shipment  nine   pasteurized-milk  i 
176*  pounds  before  and  1593  pounds  after 

pounds,  is  9.49  per  cent  of  the  original  weight  <>f  the  cheese,  in  the 
same  shipment  nine  raw-milk  cheeses  weighed  161  pounds  before  and 
pounds  after  storage.  The  loss  in  this  case,  L6J  pounds,  is 
10.09  |  er  cent  of  the  original  weight.  In  both  shipments  the  raw- 
milk  cheese  lost  a  greater  per  cent  of  their  w  eight  than  the  pasteurized- 
milk  cheese.  On  comparing  the  individual  -  in  pairs,  it  was 
found  that  in  most  cases  the  pasteurized-milk  cheese  1  Bt  Less  than 
the  raw-milk  cheese,  although  hi  a  few  true. 

The  weights  taken  at  Madison  on  the  saim  e  the 

figures  shown  in  Table  28,  agreeing  substantially  with  the  results 
obtained  at  Chicago: 

Table  2S.—Ai i 

ith. 


Method. 

i 

of  milk. 

- 

1 

! 

■ 

. 

. 



3     \ 

.."■4 

.46 

10.38 



.69 

.61 

,60 

7.10 

In  this  work. 


CHEESE    CURED   IN    WARM    ROOM. 


67 


Cheese  cured  in  a  warm  room  (lots  3D  and  4D). — To  Further  test 
the  effect  of  storage  at  high  temperature  40  cheeses,  lots  3D  and  -H). 
were  put  for  47  days  into  a  warm  curing  room  at  Madison  where  the 
temperature  was  held  at  75°  to  85°. 


TABLt;  29. — Average  yield  per  hundred  pounds  of  milk  of  run-  and  pasteurized  mill;  cheese 

cured  in  warm  room. 

Method. 

Number 

m.ike. 

'  100  pounds  of  milk. 

Lot 
No. 

Green. 

Paraf- 
fined. 

Put  in        Tata? 

room.         ™™ 
room. 

9 

Pounds. 
Ki.47 
9.  93 

Pounds. 
9.99 

Pounds.     Pounds. 
9.91  ,           9.37 

9.46  ' 

3D 

.  7.4 

.45 
4.72 

.45 

4.75 

.49 

5.52 

9 

9.92  1                               9.33 

9.31  |                              8.73 

4D 

til 

.62 
G.72 

60 

7.12 

From  these  results  with  eight  lots  of  cheese— IB,  2B,  3B,  4B,  3C, 
4C ',  3D,  and  4D — it  can  be  stated  with  certainty  that  pasteurized-milk 
cheese  does  not  lose  more  in  weight  than  raw-milk  cheese  when  stored 
in  warm  rooms  or  in  the  South,  after  paraffining.  On  the  contrary, 
the  pasteurized-milk  cheese  lost  on  the  average  a  smaller  percentage 
of  weight  in  warm  storage  than  the  raw-milk  cheese.  At  first  this 
fact  seemed  inexplicable,  but  the  reason  became  clearly  apparent  from 
inspection  of  the  cheese  kept  in  the  warm  curing  room  at  Madison. 

Within  a  few  days  after  going  into  the  warm  room  the  raw-milk 
cheese  became  very  greasy  on  the  surface,  and  the  grease  running  on 
to  the  shelves  and  the  floor  marked  the  spot  where  each  cheese  stood. 
The  pasteurized-milk  cheese,  standing  alongside  of  them  on  the  same 
shelves,  did  not  exude  grease,  or  only  very  slightly  in  a  few  cases,  and 
the  difference  between  the  greasy  raw-milk  cheese  and  the  dry  surface 
of  the  pasteurized-milk  cheese  was  so  marked  that  there  was  no 
culty  in  picking  out  each  kind  by  the  sense  of  touch  alone. 

To  demonstrate  further  the  difference  in  this  respect,  each  cheese 
of  the  last  lot  when  put  into  the  warm  room  was  placed  on  a  piece 
of  wire  gauze  in  a  shallow  tin  pan,  so  that  the  grease  running  from  each 
cheese  could  be  collected.  A  very  little  of  the  paraffin  was  scraped 
from  the  surface  of  each  cheese  by  contact  with  the  wire  gauze  in  the 
bottom  of  the  pan.  The  total  weight  of  material,  practically  all 
paraffin,  collected  from  the  10  pasteurized-milk  cheeses  weighed  0.13  of 
a  pound,  while  the  material,  mostly  fat,  with  a  little  paraffin  and  mold, 
collected  from  the  raw-milk  cheeses,  weighed  1.92  pounds,  vmich  is 
1.2  per  cent  of  the'weight  of  the  raw  cheese  when  placed  in  the  store- 
room. 


68 


CHEDDAR  RIZED    MILK. 


At  present  we  are  unable  to  explain  \\  ith  certainty  why  the  past 
ized-milk  cheese  should  losefaf  Less  readily  when  stored  al  7nc  t< 
than  the  raw-milk  cl  Further  Btudy  will  be  made  of  this  phe- 

nomenon. The  purpose  <»f  beginning  these  Btudiee  of  losses  of  weight 
in  warm  rooms  waa  to  determine  whether  the  increased  yield  obtained 
by  pasteurization  would  be  offset  by  increased  I  weight  when 

pasteurized-milk  cheese  arc  Bhipped  to  the  South,  and  it  i-  now  fully 
demonstrated  thai  the  pasteurized-milk  cheese  stored  in  the  South 
maintain  their  advantage  as  to  increased  yield. 

Cheese  placed  in  cold  storage  at  Waterloo,   R  "/•.'.     Thel 

of  weight  observed  in  35  pasteurized-milk  cheeses  put  into  cold 
Btora  •'    at  different  ages  are  Bhown  in  Table  30.     T. 

represent  Beven  days'  make  during  July  and  August,  1911. 

Table  30. — shrinkage  of  pasteurized-milk  d  <  I  storage. 


When 

parutlined. 

When  put 

When 

made. 

Weight, 

green. 

into  cold 
stoi 

out  of  cold 
:  'ge. 

Totul  shrinkage. 

Age. 

Weight. 

Age. 

Weight. 

Age. 

Weight. 

1911. 

Pounds. 

Day*. 

Pounds. 

Days. 

Pounds. 

Pounds. 

Pounds. 

Per  cent. 

Julv    19 

9 

(») 

P) 

18.15 

11.89 

10 

21.11 

1 

1 

100 

.73 

19 

20.  10 

: 

19.  21 

7 

19.  21 

100 

19.15 

19 

264-1 

21.07 

9 

14 

100 

1.22 

19 

19.  S9 

9 

28 

18.70 

100 

1.61 

19 

9 

19.44 

41 

10* J 

21 

22.49 

8 

(») 

w 

99 

21 

1 

17.58 

17.45 

.53 

21 

7 

7 

19.35 

99 

21 

18.86 

8 

17.98 

14 

99 

17.::, 

1.11 

21 

B 

18.68 

28 

18.42 

99 

1.53 

7.81 

21 

19.25 

18.40 

18.13 

99 

1.57 

21 

19.75 

8 

18.86 

40 

99 

18.10 

25  1    287-1 

-     32 

11 

19.86 

(") 

(") 

95 

-     - 

11.14 

20.29 

1 

19.95 

1 

19.  95 

95 

2.41 

19.97 

7 

19.11 

7 

19.11 

95 

1.07 

5.35 

11 

14 

- 

95 

-       3 

1.17 

5.43 

25 

.     S 

11 

29 

95 

18.58 

8.15 

22  - 

11 

43 

.       - 

95 

1.95 

18.70 

9 

17.80 

(>) 

(») 

93 

16.45 

-    . 

27 

1 

19.45 

93 

19.20 

3.42 

27 

19.83 

7 

19.01 

7 

19.01 

93 

.90 

9 

14 

19.92 

93 

19.55 

27 

18.80 

9 

17.91 

27 

17.00 

93 

27 

20.22 

9 

41 

93 

l.'.C 

Aug.     1 

21.91 

11 

(*) 

(») 

19.00 

2.  n 

13.28 

1 

272  2 

19.78 

1 

1 

19.30 

19.05 

.73 

3.09 

1 

19.40 

7 

7 

18.55 

1.18 

6.08 

1 

21.82 

11 

20.55 

14 

20.55 

7.19 

l 

21.80 

11 

29 

19.90 

1.90 

1 

21.75 

11 

40 

19.  75 

89 

19.50 

10.34 

1 

19.90 

11 

w 

(») 

13.56 

8 

276-2 

1 

1 

81 

4.01 

8 

2il.  A4 

7 

7 

M 

1.14 

5.57 

8 

19.90 

11 

15 

1.56 

7.53 

8 

19.70 

11 

18.45 

28 

is.  21 

17.75 

1 .  96 

20.  In 
19.90 

(J) 

1 

19.50 

18.10 

19.  3S 

2.  (HI 

9.95 

r 

19.68 

8 

18.81 

8 

18.81 

18.76 

.93 

4.72 

ii 

15 

17.70 

17.40 

1.40 

7.44 

19.84 

ii 

18.84 

67 

IV  4.'. 

7.00 

ii 

17.62 

42 

(■) 

>l  MM  AMY. 

i 

7 
day. 

ireek. 

7 
2  weeks. 

4  we 

7 
eks. 

6  w 

6 

eeks. 

1 

7 
n  cellar. 

1  hoi 

. 

A  \- 

shriii- 

per 

5.10 

C.  51 

8.29 

9.29 

11.78 



»  In  warehouse  at  Waterloo,  Wks.,  by  courtesy  of  the  Ko.icu  A  Seeber  Co. 


1  Cured  in  cellar. 


CAUSES  OF  INCREASED  HELD.  69 

Although  the  seven  cheeses  put  into  storage  at  the  age  of  l  day 
showed  an  average  oi'  only  3.22  per  cent  shrinkage  after  three  months, 
yet  they  wore  not  well  broken  down  and  required  further  curing  at 
60°  to  70°  to  get  rid  of  their  curdy,  lumpy  texture.  The  cheese 
paraffined  and  stored  when  1  week  old  showed  an  average  total 
shrinkage  of  5.10  per  cent,  and  these  were  found  to  be  thoroughly 
broken  dowrn  when  taken  out  of  cold  storage.  This  series  appears 
to  indicate  that  the  quality  of  pasteurized-milk  cheese  is  not  damaged 
by  placing  in  cold  storage  at  the  age  of  1  week,  while  the  shrinkage 
(5.10  per  cent)  is  about  half  that  of  the  duplicate  cheese,  cured  in 
the  cellar  at  Madison  (11.78  per  cent),  as  shown  at  the  bottom  of 
the  table. 

THE  CAUSES  OF  THE  INCREASED  YIELD  FROM  PASTEURIZED  MILK. 

THE    LOSSES    OF   FAT    FROM    VAT   AND    PRESS. 

The  increased  yield  of  green  cheese  from  pasteurized  milk,  amount- 
ing to  over  5  per  cent  (Table  20),  is  due  partly  to  the  fact  that  about 
half  of  the  fat  lost  in  the  whey  and  drippings  by  the  old  process  is 
retained  in  the  cheese  by  the  new  process  of  making.  Also  it  is 
found  that  a  little  more  moisture  can  safely  be  incorporated  in  the 
new-process  cheese  without  danger  of  spoiling  it,  but  on  the  contrary 
giving  it  a  moist,  fat  appearance  which  consumers  generally  like. 
The  loss  of  fat  in  the  whey  is  caused  partly  by  the  passage  of  the 
curd  knives  through  the  curd  in  cutting,  at  which  time  a  considerable 
proportion  of  fat  is  brushed  away  from  the  surface  of  the  curd  cubes. 
During  the  stirring  and  heating  some  further  fat  globules  are  lost 
from  the  curd  cubes,  and  still  further  losses  occur  after  milling  and 
during  pressing.  In  the  new  process  of  making  cheese  from  pasteur- 
ized milk  the.  curd  is  so  firm  and  elastic  (not  brittle)  at  the  time  of 
cutting  that  the  loss  of  fat  in  the  whey  averages  only  about  one-half 
that  observed  in  cheese  making  by  the  ordinary  process. 

The  average  fat  content  of  whey  from  good  clean  milk  is  stated  to 
be  0.30  per  cent  and  from  average  cheese  factory  milk  0.36  per  cent.1 
On  a  great  many  days  during  the  past  two  and  one-half  years  the 
milk  supply  in  the  receiving  vat  has  been  divided  and  one  half  made 
up  by  the  regular  methods  and  the  other  half  by  the  new  method. 
The  quality  and  composition  of  the  milk  was  thus  the  same  in  both 
vats.  On  the  24  days  listed  in  Table  31  the  average  fat  content  of 
the  whey  from  the  regular  vats  was  0.25  per  cent  and  from  the 
pasteurized-milk  vats  was  0.159  per  cent. 

» Van  Slyke  and  Publow,  loc.  cit.,  pp.  189, 190. 


L 


CHEDDAB    CHEESE    FBOM    PASTEUBIZED    MILK. 


TABU  81.  <>n  of  the  percentage  of  fat  in  «  I  and  by  regular 

nutl  •   making. 


milk. 

' 

of  milk 

drawn. 

whey 

drawn. 

1911. 

.; 

I 

l'er  cent. 

4   1 

0  M 

0  17 

.14 

t    1 

.15 

.') 

"*4.*6" 

.17 

7 

4.1 

.  18 

8 

.Ki 

1909. 

July  n 

.15 

.21 

.12 

4.0 

.15 

to 

.12 

12 

3.7 

.18 

- 

July    LS 

4.1 

2t>0 

.12 

Oct.     l 

4.7 

2 

4  5 

200 

.18 

7 

4.4 

.14 

.19 

8 

4.0 

.15 

Sept.    1 

4.3 

.17 

2 

4.2 

.is 

14 

12 

.  is 

.24 

16 

4.(1 

.27 

17 

4.4 

.19 

L8 

4.4 

.is 

19 

4.2 

.17 

1 

.150 

.25 

Tn  those  cases  the  small  amount  of  milk  handled  in  each  vat  per- 
mitted hand  stirring,  and  neither  the  rake  nor  the  agitator  \\ 
By  this  means  the  whey  fat  of  the  regular-process  vats  was  kept  at  a 
lower  figure,  perhaps,  than  could  have  been  done  with  large  vats, 
as  handled  in  a  commercial  factory  using  the  regular  proc< 

On  22  days,  using  l.'Joo  to  2,000  pounds  of  pasteurized  milk  in 
each  vat,  the  percentage  of  fat  in  the  whey  at  the  time  of  drawing 
the  whey  averaged  0.17  per  cent,  as  shown  in  the  following  table. 
In  the  -  the  vats  were  stirred  with  an  agitator. 

Table  32. — Fat  content  of  whey  j  teat. 


Fat  in 
whey  two 

if  tor 
cue 

:ht 
Of  milk 
bandied. 

of  cl .' 

L910. 

Jui.' 

Per  cent. 

0.14 
.  Ki 

.17 
.12 
.18 

.14 

.18 

.17 

Pound*. 

1 .  427 
1.431 

Pounds. 

144 
166 

147 

CAUSES  OF  INCREASED    HELD.  71 

Table  32. — Fui  content  of  whey  from  p<utewrized-milk  cheese — Continued. 


Date. 

Fa1  in 

\\lle 

li  mrs  .utcr 
1  utting. 

Welghl 

of  milk 
handled. 

Weight 

of  cheer. 

1910. 

Juno  M 
16 
17 
20 
21 
22 
23 
24 
28 
29 
30 

July  5 
6 

Average.. 

Per  cent. 
0. 20 

.20 
.20 
.20 
.23 
.14 
.16 
.18 
.24 
.14 
.17 
.18 
.14 

Pounds. 
L,398 
1,165 

1 ,  320 
1 ,  588 
1 ,  292 
1 ,  347 
1 ,  329 
1,337 
1,277 
1,210 
1 ,  243 
1,242 
1 ,  229 

Pounds. 

1  IS 

126 
152 

170 
144 
144 
139 
139 
130 
130 
131 
125 
134 

.17 

Most  of  the  loss  of  fat  from  curd  occurs  at  the  moment  of  cutting, 
as  shown  by  the  figures  in  Table  33.  On  23  days  samples  of  whey 
were  taken  daily  from  the  vat  as  soon  after  cutting  as  it  was  possible 
to  obtain  any  clear  whey — that  is,  in  four  to  six  minutes.  The  fat 
content  of  this  whey,  sampled  five  minutes  after  cutting,  tested  0.47 
per  cent  on  the  average  of  23  days,  while  the  average  test  of  samples 
taken  from  the  same  vats  two  hours  after  cutting  was  0.16  per  cent. 
The  average  weight  of  milk  handled  daily  in  the  vat  was  1.110 
pounds,  and  the  average  fat  test  of  the  milk  was  4  per  cent. 

Table  33. — Fat  content  ofv:hey  at  time  of  cutting  curd  and  2  hours  later. 


Time  alter  cutting 

Date. 

Weight 

of  milk- 
handled. 

Weight 
of  cheese. 

4  to  6 

2 

minutes. 

hours. 

1910. 

%fat. 

%fat. 

Pounds. 

Pounds. 

Apr.     8 

0.45 

0.16 

1.011 

102 

12 

.46 

.19 

1,011 

104 

13 

.40 

.15 

967 

98 

14 

.40 

.14 

1,045 

108 

15 

.50 

.12 

1,001 

100 

18 

.35 

.13 

993 

103 

19 

.55 

.22 

906 

97 

22 

.40 

.16 

755 

77 

25 

.42 

.19 

1,065 

117 

26 

.52 

.17 

940 

103 

27 

.52 

.16 

1,004 

109 

28 

.57 

.15 

972 

102 

29 

.45 

.14 

796 

102 

May     3 

.65 

.16 

1,041 

122 

4 

.67 

.16 

1,055 

118 

5 

.52 

.17 

1,119 

129 

6 

.50 

.20 

917 

97 

10 

.52 

.16 

1,288 

141 

11 

.50 

.15 

1,285 

138 

18 

.35 

.15 

1, 239 

137 

19 

.40 

.14 

1,186 

130 

23 

.25 

.12 

2,477 

268 

24 
Average.. 

.45 

.19 

1,454 

154 

.47 

.16 

1,110 

119.8 

f2  OHEDDAB   CHEESE    PBOM    J  ZED   MILK. 

The  reason  for  the  e  in  percentage  of  fat  in  whey  at  two 

hours  after  cutting  is  that  there  was  little  fat  lost  from  the  curd 
during  the  time  the  whey  was  being  expelled,  so  that  the  fat  lost 
from  the  curd  cubes  at  the  moment  of  cutting  was  diluted  about  0.47 
divided  by0.16    3  times  bythewatei  lied  from  the  curd  during 

the  two-hour  period. 

at  after  drawing  tlu   whey.    On  Beveral  day-  the  whey 
drippings  from  the  pasteurized-milk  curd,  from  the  time  the  curd 
was  all  on  the  rack  up  to  the  time  when  it  was  taken  from  the  pi 
were  collected,  weighed,  and  tested  for  fat.     Prom  this  could  be  cal- 
culated the  weight  of  fat  lost  in  the  drippings,  as  shown  in  Tables  34, 

Table  94.— Lost  of  fai  in  drippings  in  2  hours  and  60  m  From  dipping  to 

hooping  zed-milk  card. 


ill  of 
drip: 
collected. 

Fat  ill  drippings. 

Weight 
of  (i 
made. 

1910. 

Apr.  12 
13 
14 
15 
18 
19 

21 

22 

25 

Total 

Pound". 

28 
31 

21 

25 

21 

24 

P(T  C(lit. 

0.27 

.10 
.15 

.  is 
.12 

Pound. 
.042 

ds. 

LOO 
103 

911 

77 
117 

.544 

991 



Table  Z5.— Losses  offal  m  drippings  before  pressing  pasteurized-milk  curds. 


Drippings  In  Lj  hours— dip- 

Drippings in  1J  hours— mill- 

Date. 

ping  to  milling. 

ing  to  hooping. 

Weight 

Fat  content. 

Weight. 

Fat  content. 

1910. 

Pounds. 

Per  cent. 

Pound. 

Pounds . 

Per  cent. 

Pound. 

Pounds. 

Apr. 

35 

- 

0.007 

1.8 

0.090 

109 

.012 

- 

1<»2 

.060 

M 

3 

- 

.08 

.020 

1.8 

.(147. 

122  J 

4 

- 

.05 

.012 

1.5 

.009 

lis 

.07 

.020 

1.7 

in 

HI 

.07 

JUS 

4.0 

1.2 

141 

11 

24 

.07 

.017 

3.0 

1.0 

13 

25 

.  10 

.040 

101 

Is 

.014 

4.:, 

- 

137 

19 

.012 

1.4 

.070 

8 

.04 

.015 

1.5 

•  •  u  - 

.14 

5.0 

- 

.  UNI 

350 

.273 

53.5 

1,738 

la  ted  fur 

10  lbs.  of 

2.01 

- 

CAUSES   OF    INCREASED    HELD.  73 

Table  36. — Loss  of  fat  in  drippings  from  pastewrized-milk  cheese  in  press. 


Date. 

L910. 

May  L6-20 

Total 

:  c  u  - 
lated  lor 
lOIbs.ol 

Total 
weight 
of  cheese 
pressed. 

Total 
lit  of 
drippings. 

i  ;ii  In  drippings. 

Pounds. 

• 

Pounds. 
24 

P<r  cent. 
:',.  85 
3.  2 

Pounds. 
0.92 
1.02 

1,6S1 

56 
.33 

1.94 
.0115 

Summary  of  losses  of  fat  by  the  new  method  of  cheese  making. — The 
total  loss  of  fat  from  cheese  in  the  new  process  is  about  1.6  per  cent 
of  the  weight  of  the  cheese,  as  shown  in  the  following  summary  of 
the  preceding  tables: 

Table  37. —  Total  losses  of  fat  in  making  10  pounds  of  cheese  from  pasteurized  milk. 


Period. 


Total, 
weight. 


Fat  content. 


Loss  of 
fat  from 
cheese. 


Whey  when  drawn 

Drippings  from  curd  before  milling 

Drippings  from  curd  in  vat  after  millin 
Drippings  from  press 

Total 


Pounds. 

S7.4 

2.01 

.31 

.33 


Per  cent. 

0. 16 

.08 

1.66 

3.46 


90.05 


Pound. 

0.1400 

.0016 

.0051 

.115 


Per  cent. 
1.  400 
.016 
.051 
.115 


.1583 


1.583 


The  average  total  loss  of  fat  from  100  pounds  of  milk  handled  by 
the  new  process  of  cheese  making  is  seen  to  be  on  the  average  0.158 
pounds  of  fat,  or  a  little  less  than  4  per  cent  of  the  total  fat  content 
of  milk  containing  4  per  cent  fat.  The  loss  of  fat  from  100  pounds 
of  milk  in  ordinary  cheese  making  under  average  factory  conditions 
has  been  found  to  amount  to  0.33  of  a  pound  of  fat,  or  0.36  per  cent 
of  fat  in  the  whey,  or  9  per  cent  of  the  total  fat  content  of  the  milk.1 

It  will  be  seen  from  these  figures  that  the  loss  of  fat  is  reduced  to 
less  than  one-half  by  the  new  process  of  cheese  making.  It  might 
be  expected  from  this  statement  that  each  day's  make  of  pasteurized- 
milk  cheese  tested  by  the  Babcock  test  would  show  a  higher  percentage 
of  fat  than  the  same  day's  raw-milk  cheese.  In  Table  38,  however, 
it  is  seen  that  in  15  cases  out  of  21  the  pasteurized-milk  cheese  tested 
lower  in  fat  (0.65  per  cent  lower  on  the  average)  than  the  raw-milk 
cheese. 

THE    INCREASED    MOISTURE    CONTEXT    OF   PASTEURIZED-MILK    CHEESE. 

This  is  due  to  the  fact  that  there  is  an  increased  content  of  moisture 
as  well  as  of  fat  in  the  new-process  cheese,  and  in  most  cases  the  in- 
crease  of   moisture   is   greater   than   the   increase   of  fat.     On   this 


Van  Slyke  and  Publow,  loc.  cit.,  p.  189. 


:  I 


CHEDDAB   CHEESE    FROM    PASTEURIZED    MII.K. 


account  the  moisture  content  of  pasteurized  cheese  listed  in  the 
table  below  Lb  greater  than  that  of  the  raw-milk  cheese  in  29  cases 
out  of  33,  and  the  avera  atage  was  L.68  greater. 

The  cheeses  listed  in  the  table  were  the  Bame  as  those  in  Table 
and  the  testing  for  fat  and  moisture  was  done  immediately  after  the 
;hta  had   been   taken  f<>r  the  determination  of  yield  and 
shrinkage.     The  samples  of  cheese  weighed  into  the  Babcock 
bottles  were  rapidly  dissolved  in  a  mixture  of  hot   water  and  >ul- 
phuric  acid,  b  d  by  one  of  us  in  a  previous  paper.1 

/  milk 


Data.  ' 

lied. 

Raw. 

DIflei 

1911. 
Feb.  24 
27 
28 

.Mar.      1 
_> 

3 

7 

B 

10 
13 

14 
15 
16 

17 

21 
22 

Apr.     5 

11 
13 

17 
is 
24 

Max       2 

- 
in 
15 
17 

A\  • 

31.60 
31.05 
31.90 

32.  r. 

33.  15 

31.62 

34.  15 
32.  90 

34. 10 

31.78 

32.  28 
34.  17 
31.02 

31.87 

P(TCt. 

30.  15 

30.75 
31.47 

30.  17 

31.45 
30.00 
31.95 

30.  >7 

30.  in 
32.  20 

3t.97 

30.  15 
32.70 

3.40 
.85 

I',  ret. 

+  l'(TCt. 

2.  15 

1 .  15 
1.00 

3.  15 

.17 



.04 

1.  It 

5 
1.85 

1.61 
1.92 

41.43 

.1^ 
1.13 

1.  15 

.15 
1.82 

1 .  _'n 

.01 

.71 

32.  09 

.01 

38.59 

.05 

.26 

The  combined  effect  upon  the  percentage  composition  of  ch< 
caused  by  increasing  both  the  fat  and  moisture  content  is  Bhown  in 

the  following  example: 

Ten  pounds  of  raw-milk  cheese  of  the  same  average  percentage 
composition  as  in  Table  shown  at  1.  below,  would  contain  the 

weights  of  fat,  moisture,  and  casein,  etc..  shown  at  II.  if  by  pas- 
teurization the  fat.  content  of  the  cheese  is  increased  ahout  1  per  cent 
of  itself,  ami  the  moisture  content  i^  increased  ahout  li'^  per  cenl  of 
itself,  there  will  he  ohtained  L0.54  pounds  of  pasteurized-milk  el 

.  '.est.    Journal  of  Industrial  aiid 

-  •        .  lag.,  utw. 


QUALITY   OF   PASTEURIZED-MILK   CHEESE.  7.") 

as  shown  at  III  instead  of  10  pounds  of  raw-milk  cheese,  a  theoretical 
gain  of  5.4  per  cent  in  the  yield  of  cheese.  (The  actual  gain  shown 
in  Table  20  was  5.37  per  cent.)  The  percentage  composition  of  this 
pasteurized  cheese  will  be  as  shown  at  IV,  which  agrees  closely  with 
the  average  composition  of  the  pasteurized-milk  cheese  .shown  a1  the 
bottom  of  Table  38. 

I.  II.  III.  IV. 

Far 3S.V)  per  cent,  3.859  pounds+0.154  pounds=4.013  pounds.  38.07  per  cent- 

Moisture..  31.28  per  cent.  3.128  pounds+0. 391  pounds=3. 519  pounds.  :;:;.:;:  percent, 

i. etc.  30.13  per  cent.  3.013  pounds+.  ---  pounds=3. 013  pounds.  28.57  per  cent. 


100.00  per  cent.  10.000  pounds.  10.545  pounds.  100.00  per  cent. 

The  increased  moisture  content  of  pasteurized-milk  cheese  made 
by  this  process  is  due  to  the  effect  of  pasteurization  on  the  properties 
of  curd,  as  stated  on  page  25. 

THE    QUALITY    OF   PASTEURIZED-MILK    CHEESE. 

SCORES    AND    CRITICISMS    OF    PASTEURIZED    AND    RAW   MILK    CHEESE. 

The  milk  supply  used  at  Madison  is  no  better  than  the  average 
cheese-factory  milk.  Sunday's  milk  is  delivered  on  Monday  through- 
out the  year  and  is  therefore  inferior  to  that  of  the  other  days.  Cheese 
from  every  day's  make  during  the  season  was  scored  by  two  judges, 
Mr.  U.  S.  Baer,  assistant  dairy  and  food  commissioner  of  the  State  of 
Wisconsin,  and  Mr.  A.  T.  Bruhn,  junior  dairyman,  United  States 
Department  of  Agriculture,  who  during  the  past  year  have  scored  the 
cheese  sent  to  the  monthly  scoring  exhibition,  conducted  by  the 
Wisconsin  Experiment  Station.  The  judges  worked  independently 
and  pinned  their  scoresheets  to  each  cheese  without  knowing  even  the 
numbers  of  the  cheese,  which  were  turned  toward  the  wall.  Their 
scores  show  close  agreement  with  each  other  in  most  cases  and  leave 
no  doubt  as  to  the  relative  quality  of  the  cheese  scored.  After 
finishing  about  20  of  the  cheeses,  they  turned  them  around  and  added 
the  cheese  numbers  to  the  sheets.  In  general,  a  score  of  92  or  above 
indicates  that  the  cheese  is  of  good  quality  and  salable  at  full  market 
price.  A  cheese  scored  below  92  is  likely  to  be  cut  in  price  in  a  dull 
market.  Tables  39  to  46  show  the  scores  of  both  judges  as  well  as 
the  average  scores,  which  latter  are  used  in  the  discussion.  Raw-milk 
cheese  is  in  all  cases  indicated  by  the  letter  C  attached  to  the  serial 
number. 

CHEESE    CURED    AT    MADISON    AT    NORMAL   TEMPERATURE. 

Lots  lAj  2 A,  3 A,  and  J+A. — These  lots  include  53  pairs  of  cheese 
cured  in  the  cellar  at  Madison.  The  temperature  of  the  curing  room 
showed  daily  about  3°  to  5°  difference  between  maximum  and  mini- 
mum and  ranged  from  60°  to  73°  from  February  to  July,  1911.  By 
opening  the  windows  at  night  only,  it  was  kept  at  60°  to  70°  from 
July  to  October. 


76 


CITEDDA1  5E    i  ROM    PAS!  EURIZED    MILK. 


rIli<  of  the  53  pairs  of  chi  as  shown  in  Table  39. 

The  re  of  all  the  pasteurized-milk  < i]  ■  •  _* . 7 r>  and  of 

the  raw-milk  cheese  v.' 

>"sc  (lots  1 
'/  lit    M<ni> 

LA   AM*  2A,  91  OBED  Jl  l.v   17,  1*1 1  - 


'lVm- 

BruhiL 

curing 

room 
B  a.  in. 

vor. 

Hire. 

To'ul. 

lore. 

Total. 

ture. 

•F. 

1911. 

Feb.  24 

172 

41.0 

92.0 

40.0 

91.5 

40.50 

24 

172C 

27.0 

27 

42.5 

28.0 

27 

40.0 

27.0 

92.0 

27.00 

91.00 

174 

41.0 

41.0 

41.00 

174C 

90.0 

Mar.     1 

17:. 

41.(1 

27.0 

40.0 

20. 0 

91.0 

92.00 

1 

175C 

40.0 

91. 0 

40.0 

1 

178 

40.0 

93.0 

41.0 

93.0 

40.50 

93.00 

9 

176C 

37.0 

27.0 

39.0 

27.0 

91.0 

27.00 

90.00 

3 

177 

40.0 

92.0 

40.0 

91.5 

91.75 

3 

177C 

26.00 

: 

178 

40.0 

91.0 

40.0 

27.0 

40.00 

91.50 

7 

178C 

27.0 

90.0 

"     91.0 

27.00 

90.50 

8 

179 

92.0 

41.0 

8 

179C 

35.0 

26.0 

- 

0 

180 

41.0 

20. 0 

92.0 

41.0 

27.0 

93.0 

41.00 

92.50 

9 

39.0 

26.  0 

90.0 

40.5 

92.0 

91.00 

10 

181 

41.0 

26. 0 

92.0 

42.0 

27.0 

41.50 

93.00 

Id 

181C 

27.0 

39.0 

90.25 

13 

182 

40.0 

41.0 

27.00 

92.50 

13 

182C 

41.0 

92.0 

40.0 

14 

183 

40.0 

91.0 

40.0 

40.00 

91.25 

14 

40.0 

92.0 

40.0 

91.5 

40.00 

15 

184 

40.0 

26. 0 

91.0 

41.0 

27.0 

40.50 

15 

184C 

40.0 

92.0 

41.5 

27.0 

" 

go" 

16 

185 

40.0 

41. 5 

10 

l?5C 

20.  0 

41.0 

27.0 

17 

186 

42.0 

28.0 

41.0 

41.50 

17 

!8fC 

41.0 

94.0 

41    (i 

27.0 

93.0 

41.00 

03" 

20 

187 

43.0 

27.0 

95.0 

41.0 

20 

187C 

35.0 

25.0 

39.0 

■ 

37.00 

21 

188 

43.0 

•_n.ii 

96.0 

41.0 

93.  0 

21 

188C 

38.0 

40  0 

27.0 

39.00 

'"go* 

22 

189 

43.0 

27.0 

95.0 

95.00 

22 

189C 

39.0 

27.0 

91.0 

39.50 

"'& 

Apr.     5 

198 

43.0 

27.0 

42.0 

5 

198C 

41.0 

27.0 

93.0 

41.5 

7 

42.0 

•J7.ii 

(14.0 

42.  0 

"4.0 

"'ei' 

7 

200C 

35.0 

40.0 

! 

91.0 

11 

202 

42.0 

20.  0 

93.0 

27.0 

11 

202C 

26. 0 

90.0 

27.0 

39.50 

91.00 

13 

•_>,  .4 

41.0 

27.0 

93.0 

42.0 

- 

41.50 

94.00 

39.0 

20.  0 

90.0 

4O.0 

27.0 

39.50 

91  00 

17 

41.0 

93.0 

41.0 

27.0 

93.0 

41.00 

93.00 

17 

206C 

40.0 

90.0 

38.0 

25.0 

S7.0 

39.00 

18 

43.0 

20.0 

94.0 

41.5 

27.0 

18 

42.0 

92.0 

40.0 

90.0 

41.1X1 

9]  00 

24 

211 

43.0 

26.0 

94.0 

42.0 

27.0 

211C 

2.-..0 

ftg  (i 

39.0 

27.  0 

91.0 

39.00 

90.00 

•_>7 

214 

40.0 

42.  5 

27.  0 

27 

214C 

37.0 

24.0 

- 

37. 0 

37.00 

R7.00 

28 

215 

42.0 

94  0 

42.0 

27.0 

42.00 

27.00 

94  00 

37.0 

B7.0 

a 

211 

41.0 

26.  0 

92.0 

40.5 

"l  6 

•1   78 

■ 

2 

21  C 

37.0 

\i:>.o 

S7.0 

n  0 

vv  00 

3 

217 

42.  0 

95.0 

41.5 

27.0 

41    77. 

3 

217C 

37.0 

^7.0 

40.0 

26. 0 

91.0 

B 

220 

41.0 

27.  0 

93.0 

42.0 

27.  0 

94.0 

41.50 

27.00 

^ 

25  0 

«4.0 

25.0 

36. 50 

in 

40.0 

25.0 

90.0 

40.0 

27.0 

40.00 

"1.00 

10 

2224  J 

37.0 

- 

40.0 

91.0 

-   • 

R9.  00 

15 

225 

40  0 

24    Q 

"1   (i 

4  2.0 

41  00 

27.00      93.00 

'"&' 

15 

vi  n 

27.0 

rM.O 

17 

41.0 

'.'2.  0 

41 .0 

27.0 

41.00 

17 

35.0 

24.0 

B4.0 

37.0 

25.0 

36.00 

S5.50 

"C"  In  this  column  indicates  raw-milk  cheese. 


QUALITY    OF    PAST  I :  I '  HI/.  KM    MILK    CHEESE. 


77 


Table  39. — Scores  of  58  pairs  of  raw  and  pasteurized  cheese  (lots  1 A       l       I   and  LI) 

cured  at  Madison    Cum  Lnued. 

LOT  3a,  scored  AUGUST  14,  1911. 


Tem- 
pera- 
ture of 

Date 

Cheese 

Scored  by  U.S.  Baer. 

Scored 

by  A.T. 

Bruhn. 

curing 
room 

s  a.  in. 

made. 

No.1 

Fla- 
vor. 

Tex- 
ture. 

Total. 

Flavor. 

Tex- 
ture. 

Total. 

Flavor. 

Tex- 
ture. 

Total. 

•F. 

1911. 

67 

May   22 

230 

43.0 

27.0 

95.0 

41.5 

26.5 

93.0 

42.  25 

26.  75 

94.00 

'     22 

230C 

40.0 

26.0 

91.0 

37.0 

25.0 

S7.0 

38.50 

25.50 

SO.  00 

66 

25 

233 

41.0 

25.0 

91.0 

41.0 

26. 0 

92. 0 

41.00 

25.50 

91.50 

25 

233C 

38.0 

25.0 

88.0 

36. 0 

25.0 

86.0 

37.00 

25.00 

S7.00 

29 

234 

42.0 

27.0 

94.0 

42.0 

27.0 

94.0 

42.00 

27.00 

94.00 

•      29 

234C 

39.0 

25.0 

89.0 

37.0 

25.0 

87.0 

38. 00 

25.00 

88. 00 

June     1 

237 

42.0 

27.0 

94.0 

41.0 

26.  5 

92.5 

41.50 

26.  75 

93.25 

6G 

1 

237C 

35.0 

25.0 

85.0 

38.0 

26.  0 

89.0 

36.50 

25.00 

87.00 

2 

23S 

40.0 

26.0 

91.0 

41.0 

26.5 

92.5 

40.50 

26.25 

91.75 

66 

2 

238C 

37.0 

26.0 

8S.0 

37.0 

25.5 

S7.5 

37.00 

25.75 

87.75 

7 

240 

40.0 

27.0 

92.0 

41.0 

26.0 

92.0 

40.50 

26. 50 

92.00 

66 

7 

240C 

33.0 

25.0 

83.0 

37.0 

26.  0 

88.0 

35. 00 

25.50 

85.50 

9 

242 

39.0 

27.0 

91.0 

41.5 

26.0 

92.5 

40.25 

26. 50 

91 .  75 

70 

9 

242C 

39.0 

26.0 

90.0 

38.0 

26. 0 

89.0 

38.50 

26.  00 

89. 50 

13 

243 

40.0 

27.0 

92.0 

41.0 

26.0 

92.0 

40.50 

26.50 

92. 00 

68 

13 

243C 

38.0 

25.0 

88.0 

38.0 

25.0 

88.0 

38.00 

25.  00 

88.00 

15 

245 

41.0 

27.0 

93.0 

41.5 

27.0 

93.5 

41.25 

27.  00 

93.25 

66 

15 

245C 

37.0 

26.0 

88.0 

40.0 

26.0 

91.0 

23. 50 

26. 00 

89.50 

16 

246 

40.0 

27.0 

92.0 

40.0 

26.0 

91.0 

40.00 

26.50 

91.50 

66 

16 

246C 

40.0 

26.0 

91.0 

39.0 

27.0 

91.0 

39.50 

26.50 

91.00 

LOT  4A,  SCORED   SEPTEMBER   18,  1911. 


June  19 
19 
21 
21 
26 
26 
27 
27 


July 


248 
248C 

250 
250C 

253 
253C 

254 
2540 

255 
255C 

258 
258C 

260 
260C 

261 
261C 

212 
262C 

2C  3 
263C 


42.0 
40.5 
40.0 
37.0 
37.0 
35.0 
41.0 
3/.0 
41.0 
35.0 
40.0 
35.0 
41.0 
37.0 
40.0 
38.0 
41.0 
37.0 
40.0 
35.0 


27.0 
26.0 
26.0 
25.0 
25.0 
25.0 
27.0 
26.0 
27.0 
25.0 
27.0 
25.0 
27.0 
25.0 
25.0 
27.0 
27.0 
26.0 
26.0 
26.0 


94.0 
91.5 
91.0 
87.0 
87.0 
85.0 
93.0 
88.0 
93.0 
85.0 
92.0 
85.0 
93.0 
87.0 
90.0 
90.0 
93.0 
88.0 
91.0 
86.0 


42.0 
40.0 
41.0 
38.0 
39.0 
35.0 
41.0 
37.0 
41.0 
37.0 
40.5 
35.0 
41.0 
36.0 
39.5 
38.0 
41.0 
37.0 
40.0 
35.0 


27.0 
20.5 
26.5 
25.0 
25.0 
26.0 
27.0 
26.  0 
27.0 
25.5 
26.5 
25.0 
26.5 
25.0 
26.0 
27.0 
26.5 
25.5 
26.0 
26.0 


94.0 
91.5 
92.5 
88.0 
89.0 
86.0 
93.0 
88.0 
93.0 
87.5 
92.0 
85.0 
92.5 
86.0 
90.5 
90.0 
92.5 
87.5 
91.0 
86.0 


42.00 
40.25 
40.50 
37.50 
38.00 
35. 00 
41.00 
37.00 
41.00 
36.00 
40.  25 
35.00 
41.00 
30.50 
39.  75 
38.00 
41.00 
37.00 
40.00 
35.00 


27.00 
26.  25 
26. 25 
25. 00 
25. 00 
25.50 
27.00 
26. 00 
27.00 
25.25 
26. 75 
25.00 
26.75 
25.00 
25.50 
27.00 
26.  75 
25.75 
26.00 
26.00 


94.00 
91.50 
91.75 
87.50 
88.00 
85.50 
93.00 
88.00 
93.00 
86. 25 
92.00 
85.00 
92.75 
86. 50 
90. 25 
90. 00 
92.75 
87.75 
91.00 
86.00 


"C"  in  this  column  indicates  raw-milk  cheese. 


In  51  cases  out  of  the  53  in  the  table  the  pasteurized-milk  cheese 
received  a  higher  average  total  score  than  the  raw-milk  cheese; 
but  in  two  cases  the  raw-milk  cheese  scored  one-fourth  to  one- 
half  a  point  higher  (Nos.  183  and  184).  In  the  51  cases  just 
mentioned  the  differences  in  total  score  between  pasteurized  and 
raw  milk  cheese  ranged  from  one-fourth  of  a  point  to  7  points  and 
averaged  3.82  points.  In  four-fifths  of  these  cases  the  difference  in 
the  score  was  over  2  points.  In  49  of  the  53  raw-milk  cheeses  the 
average  score  was  below  92,  while  39  of  the  53  pasteurized-milk 
cheeses  scored  92  or  above.  The  distribution  of  the  scores  in  each 
case  is  most  clearly  shown  in  figure  3. 


78 


CHEDDAR    CHEESE    FROM     PASTEURIZED    MILK. 


It  can  readily  be  seen  From  figure  3  that  hi  per  cent  (60  out  oi 
of  the  pasteurized  cheese  scores  lie  between  '.'l  and  95,  a  range  of  i 
points,  while  the  same  proportion  (9  i  per  cent    of  the  raw-milk  cl 
scores  are  quite  uniformly  distributed  between  85  and  92,  a  ran 
7  points. 

The  variation  in  quality  of  product  from  day  to  <la\  is  thus  reduced 

nearly  one  -  half  l>v 


P/4STEU&/ZEQ-M/LK'  CHEESE 

::     :     : 

•••  ••••  •• 

•  ••••§•••••••    • 


RAW-M/LK  CHEESE 

i   ... 

:     .  :  .::     :  :  :•• 

. .  ...  .......  ... 


85      86      87 


39       90      91        92      93 
TOTAL  3-CO/PFS. 


94       95      96 


Fig.  3.— Distribution  of  total  scores  of  pasteurized  and  yaw  milk  cheese. 


t he  new  process.  In 
scoring  all  o 
cheeses  t  tie  color  and 
make-up  were  al- 
ways marked  per- 
fect .  and  the  ch< 
were  marked  off 
only  on  flavor  and 
texture.  It  is  of  in- 
terest therefore  to  consider  the  flavor  and  texture  scores  separately, 
in  addition  to  the  discussion  of  total  -iveii  abo 

The  average  flavor  score  for  all  of  the  pasteurized  cheese  Is  41.05 
and  for  the  raw-milk  cl,  $.13.     In  50  cases  out  of  53  the  pas- 

teurized-milk   cheese   lias   a   higher   average  l!  ore  than  the 

raw,  in  2  cases  the  scores  are  equal,  and  in  1  case  the  uized 

cheese  is  one-fourth  point  less  than  the  raw. 

In    the    50    cases 

just  mentioned  the 
difference  in  the  fla- 
vor score  between 
the  two  makes  of 
cheese  ranged  from 
0.50  to  5.50  points, 
averaging  3.1  points. 
The  difference  was 
equal  to  or  greater 
than.  L.25  points  in 
47  out  of  the  50 
-.  showing  that 
the  improvement  in 
flavor  through  pas- 
teurization was  not 
only  unquestionable,  but  also  consistent.  In  51  out  of  the 
the  pasteurized-milk  ch<  )  or  above  for  flavor,  while  45 

out  of  the  53  raw-milk  che<  ed  below  40  Tor  flavor. 

Figure  1  shows  that  94  per  cent  (50  out  of  53)  of  the  pasteurized 
cheese  flavor  scores  lie  between  40  and  42J,  a  range  of  2\  points: 
while  the  raw-milk  cheese  flavor  scores  are  quite  evenly  distributed 


P/tSTEOR/ZeO-M/l/f  CN££5£- 

M 


•    • 


•    i 
•••••••    ••• 

•••••••••••• 


•  • 


&A  W-M/LK  CHEESE 


•  •   f 

•  •  * 


•  • 


•  ••••••••       • 


36      37 


38      39      40      4/ 


42      43 


Distribution  of  flavor  scores  of  pa  iw  milk 


PASrEUR/ZED 

-M/Uf  CHEESE* 

• 

Li 

.  :  Hilh 

• 

RAW-M/LK 
CHEESE 

• 

• 
• 

i  i 

•  • 

•  • 

i  •  : 

%     :     : 

•     •     # 

•    •    o         c 
•    •So         • 

: 

2* 

25                26                27 

23 

CIIKKSK   (  rilKD    IN     iiir.    SOUTH.  79 

aver  a  range  of  5  points  (from  :;">  to  40  or  11  >.  The  range  of  varia- 
tion is  thus  twice  as  great  in  the  raw  as  it  is  in  the  pasteurized,  show- 
ing thai  the  daily  variation  of  flavor  is  reduced  about  one-half  by 
the  new  process. 

The  average  texture  scores  show  also  some  advantage  for  the  new- 
process  cheese.  The  average  texture  score  on  all  of  the  pasteurized- 
milk  cheese  was  26.70,  and  on  the  raw-milk  cheese  25.96. 

In  40  cases  out  of  53  the  pasteurized  cheese  scored  higher  than  the 
raw,  in  live  cases  the  scores  were4  equal,  and  in  8  cases  the  pasteurized 
cheese  scored  0.25  to  1.5  points  (average  0.59  point)  lower  than  the 
raw.  Among  the  40  cases  just  mentioned,  the  differences  in  texture 
score  between  the  two 
makes  ranged  from 
0.25  to  2  points,  and 
averaged  1.09  points. 

Figure  5  shows  that 
90  per  cent  (48  out  of 
53)  of  the  pasteurized- 
milk  cheese  texture 
scores  lie  between  26 
and  27.50;  a  range  of 
1.50  points;  while  94 
per  cent  (50  out  of  53) 
of  the  raw-milk  cheese 

scores  are  quite  evenly  distributed  between  25  and  27,  a  range  of  2 
points,  a  distinct  advantage  in  favor  of  the  new  process,  both  as  to 
quality  and  uniformity  of  texture. 

CHEESE  CURED  IN  THE  SOUTH. 

Lot  IB. — Four  lots  of  cheese,  lots  IB,  2B,  3B,  and  4B,  were  shipped 
to  Xew  Orleans  for  storage,  the  first  lot  for  two  months  and  the  other 
three  for  one  month. 

Lot  IB  consisted  of  25  pairs  of  cheese  which  were  made  on  25  days 
between  February  23  and  April  18,  at  Madison,  and  shipped  to  Xew 
Orleans  April  29,  arriving  May  9.  They  were  stored  there  until  July 
3,  and  then  shipped  back  to  Madison  where  they  were  scored  sepa- 
rately on  July  17,  1911,  by  Messrs.  U.  S.  Baer  and  A.  T.  Bruhn.  The 
temperatures  at  Xew  Orleans  given  below  are  taken  from  the  United 
States  Weather  Bureau  monthly  meteorological  summaries.  The 
average  daily  mean  for  May  was  75.8°,  with  temperature  on  different 
days  varying  from  60  to  96.  For  June  the  average  daily  mean  was 
83.2°,  with  temperature  on  different  days  varying  from  70  to  98. 
The  quality  of  both  the  raw  and  pasteurized  cheese  after  returning 
from  Xew  Orleans  was  very  poor,  as  shown  by  the  scores  of  the  judges 
and  by  letters  from  dealers  to  whom  they  were  afterwards  sold  at  a 


FIG. 5.— Distribution  of  texture  scores  of  pasteurized  and  raw  milk 
cheese. 


80 


CHEDDAB    CHEESE    FROM    PASTEURIZED    MILK. 


reduced  price.     The  >re  of  the  25  pasteurized-milk  ch< 

35.10  and  of  the  25  raw-milk  <  .  a  difference  of  1.76 

points.     In   17  cases  out  of  25  the  pasteurized-milk  chees 
higher,  b  [ual  to,  and  in  5  cases  Less  than  the  raw-milk 

chees*  Table  40.)     The  highest   avei  ire  given   to  any 

cheese  in  the  lot   wi  and  the  lowest    78.50.     The  scores  are 

Bhown  in  Table  40. 

arj  of  rati  *  tuu 

■ 


Date  ma  le. 

Bruhn). 

191L 

171 

81 

171C 

^7 

^7 

-7 

172 

-1 

24 

172C 

• 

28 

174 

- 

28 

17IC 

84 

Mar.     1 

175 

" 

1 

175C 

- 

84 

2 

L76 

- 

88 

87 

2 

176C 

3 

177 

84 

3 

177C 

7 

3 

- 

- 

7 

- 

8 

179 

01 

8 

179C 

S 

84 

9 

180 

^7 

9 

I80C 

33 

85 

10 

181 

88 

10 

181C 

- 

85 

13 

182 

S 

80 

3 

13 

§ 

80 

14 

S 

14 

15 

35 

15 

85 

32 

16 

B5 

18 

3S 

85 

ss 

17 

5 

17 

B 

8 

20 

79 

S 

30 

187C 

21 

77 

21 

80 

- 

189 

- 

s 

189C 

- 

80 

V  ' 

• 

" 

5 

198C 

81 

7 

- 

^7 

7 

200C 

32 

11 

M 

89 

11 

- 

13 

2M 

13 

84 

17 

i 

17 

- 

207 

Jf 

18 

8 

»  "C"  in  this  column  indicates  raw- 


CHEESE   CURED   IX    THE    BOUTH.  81 

It  can  be  soon  that  storage  for  so  long  a  period  as  two  months  in 
New  Orleans,  at  such  temperatures,  can  not  be  practiced  with  either 
raw  or  pasteurized  cheese  without  great  loss  of  quality;  and  that  of 
the  two  lots,  the  pasteurized  was  somewhat  the  better  when  taken 
out  of  storage.  On  account  of  the  unmarketable  quality  of  both  Lots 
of  cheese  when  scored  it  appears  unnecessary  to  give  the  detailed 
score  and  criticisms  as  to  flavor  and  texture. 

Lots  2B,  SB,  and  4B. — These  lots  were  stored  at  New  Orleans  for  one 
month  each  during  parts  of  June,  July,  August,  and  September,  1911. 
The  mean  daily  temperature  during  this  period  averaged  83.2°  for 
June,  80.2°  for  July,  81.8°  for  August,  and  82.6°  for  September.  In 
lot  2B  the  9  pasteurized-milk  cheeses  received  an  average  total  score 
of  90.44,  and  the  raw-milk  cheese  of  85.56.  The  pasteurized  was 
better  in  every  case,  and  on  the  average  4.88  points  better. 


PASrEUP/ZED-M/Ltf  CHEESE                                     \            \ 

•                    •            • 

•  •                                              •••••• 

•  •                             •       •••••§••       •• 

••••       ••                         •        ••••   •••   ••••••  ••• 

•  • 

PAW-M/LK  CHEESE 

•  • 

•  • 

•  •    • 

•  •     • 

•  •    • 

•  •           •     • 

.iltiii... 

77        76        79        60        81         62 

63        84        SS       66        67        86        89 
TOT/4L.    ^CO&tt. 

90        91        92 

33 

Fig.  6.— Distribution  of  total  scores  of  pasteurized  and  raw  milk  cheese. 

In  lot  3B  the  10  pasteurized-milk  cheeses  scored  the  highest  in 
every  case,  the  average  being  7.7  points  higher.  The  average  score  of 
the  pasteurized  was  90.30,  and  of  the  raw  82.60. 

In  lot  4B  the  10  pasteurized-milk  cheeses  scored  the  highest  in 
every  case  but  one,  and  averaged  85.62,  while  the  10  raw-milk 
cheeses  averaged  82.10,  a  difference  of  3.52  points. 

From  the  results  shown  in  Tables  40  and  41  and  in  figure  6,  it  is 
clear  that  after  storage  in  the  South  the  pasteurized-milk  cheese 
came  out  better  in  quality  than  the  raw-milk  cheese  made  from  the 
same  milk.  It  is  not  intended  to  suggest  that  cheese  could  be  shipped 
to  the  Southern  States  with  the  express  intention  of  storing  it  for  one 
month  before  it  is  sold,  but  it  is  clear  that  during  the  few  days  or 
Weeks  necessarily  elapsing  after  market  cheese  reaches  its  destination 
in  the  South  and  before  it  is  eaten,  the  pasteurized-milk  cheese  is 
less  likely  to  undergo  serious  deterioration  than  the  raw-milk  cheese. 
79994°--Bull.  165—13 6 


B2 


('II  EDDAR    <lll  ESE    1  l;»»M     PAS!  EURIZED    Mil  K. 


Tabu  B  SB,  and  4B)  cured 

LOl   .1.    »  OB]  l-  JULY  17.  1011    at  IfADIBON. 


nude 

tempera- 
Orleans. 

Total 

Bruhn). 

total 

mi. 

Apr 

24 
27 

8 
B 

s 

in 

10 

is 

IS 
17 

17 

•J». 

211 
21 1C 

m 

215C 

217 
217C 

227 

90 
85 

8.5 

■ 

91 

85 

85 

88 
B4 

87 

58 

- 

91 

86 

89 

7.1 

LOT  3B,  8CORED  AUG.  14.  1911,  AT  MADISON. 


Ifaj 

25 

28 

June     1 
1 

2 
2 

g 
13 
13 
IS 
IS 
16 
16 

230 

240 
240C 

246C 

89 
83 
90 

21 

91 

80 
'.'1 
95 

93 
82 

- 

B7 

89 

86 

38 

84 

88 

90 
82 

81 

Bl 

•to.  5 

91 

85 

82 

89 
B4 

S3 

5 

g 

87 

38 

LOT  n;   SCORED  SEPT.  18,  1911,  AT  M  IDIS<  »N 


June   19 
L9 
21 
21 
26 

27 

Julv      3 
3 

B 

10 

in 
11 

li 

12 
12 

78 

248 

264 

- 

261 
261C 

Bl 
BS 

B7 

7^ 

B2 
B8 

- 

90 

BS 

B7 

- 

38 

BS 

- 

77 
3 

BS 
38 

8 

78 

- 

B4 

B 

89 

77 

77.:. 

8 
88 

Bl 
8 

32 

■ 


CHEESE   CURED   IN    TIIE    SOUTH. 


83 


Lota  SC  and  /+C.  These  two  additional  lots  were  Btored  for  one 
month  in  the  South  and  subsequently  scored  at  Madison.  In  lot 
3C  the  10  pasteurized  cheeses  averaged  (.)l  and  the  10  raw-milk 
cheeses  84.85,  as  shown  in  Table  42.  In  every  case  the  pasteurized 
cheese  scored  higher  than  the  raw.  In  Lot  4C,  the  10  pasteurized 
averaged  87.82  in  total  score,  and  the  10  raw-milk  cheeses,  85.07,  and 
in  every  case  but  one  the  pasteurized  scored  higher  than  the  raw. 
All  but  two  of  these  40  cheeses  scored  below  92  and  most  of  them  w  ere 
unsalable  at  full  price,  after  storage  as  described.  The  temperature 
inside  of  the  storage  warehouse  was  not  recorded. 

Table  42. — Scores  of  20  pairs  of  raw  and  pasteurized  milk  cheese  (lots  3C  and  4C)  stored 
one  month  in  the  South  and  scored  at  Madison. 

LOT  3C,   STORED  ONE   MONTH  AT  COLUMBUS,   GA.,   AND  SCORED   AT  MADISON,   AUG.  14,  1911. 


Date 
made. 

Cheese 
No.i 

Total  score 
(U.S. 
Baer). 

Total  score 
(A.T. 
Bruhn). 

A  vrrage 
total  score. 

1911. 

Apr.   22 

230 

90 

90 

90 

22 

230C 

87 

86 

86.5 

25 

233 

90 

89i 

89.75 

25 

233C 

85 

84 

84.5 

29 

234 

94 

94 

94 

29 

234C 

91 

87 

89 

June     1 

237 

92 

89 

90.5 

1 

237C 

85 

83 

84 

2 

238 

90 

91 

90.5 

2 

2380 

84 

85 

84.5 

7 

240 

92 

91 

91.5 

7 

240O 

78 

79 

78.5 

9 

242 

91 

93 

92 

9 

242C 

85 

87 

86 

13 

243 

Lost. 

Lost. 

Lost. 

13 

243C 

85 

82 

83.5 

15 

245 

91 

90 

90.5 

15 

245C 

89 

84 

86.5 

16 

246 

90 

901 

90.25 

16 

246C 

88 

83 

85.5 

LOT  4C,   STORED  ONE  MONTH  AT  NEW  ORLEANS,    AND  SCORED   AT  M/.DISON,  SEPT.   18,   1911. 


1911. 

June  19 

248 

90 

891 

89.75 

19 

248C 

85 

86" 

85.5 

21 

250 

88 

88 

88 

21 

250C 

85 

85 

85 

26 

253 

86 

87 

86.5 

26 

253C 

86 

85* 

85.  75 

27 

254 

90 

m 

89.75 

27 

254C 

80 

83 

81.5 

28 

255 

89* 

89* 

89.5 

28 

255C 

83 

85 

84 

July     3 

258 

87 

88 

87.5 

3 

2580 

86 

86 

86 

8 

260 

89 

90 

89.5 

8 

260C 

87 

86 

86.5 

10 

261 

83 

84 

83.5 

10 

261C 

87 

86 

86.5 

11 

262 

85 

85 

85 

11 

262C 

85 

85 

85 

12 

263 

90 

88* 

89.  25 

12 

263C 

85 

85 

85 

i  "C'-  indicates  raw-milk  cheese. 


E  I 


OH  EDDAB    (II  I  l  si.    I  ROM    PAS!  El   RIZED    MILK. 


•  in  i  -i     CUBBD   is    uak\i    BOOM    at    MADISON. 

Lots  SD  and  \D.  These  lots  of  cheese  were  stored  in  ■  warm  room 
at  Madison  where  fche  temperature  ranged  from  7oJ  to  80°,  occasion- 
ally going  up  to  s"»  .  during  the  months  of  July,  Augusl ,  and  Septem- 
ber, 1911.  In  lol  3D  ill*'  pasteurized  cheese  scored  higher  than  the 
raw -milk  cheese  in  every  case,  averaging  90.55  to  total  score,  while 
the  raw -milk  cheese  averaged  83.75.  In  Lof  1 1  >  the  pasteurized  cheese 
scored  higher  than  the  raw  in  every  case  bul  one,  averaging  90.52, 
while  the  raw-milk  cheese  averaged  86.15,  as  shown  in  Table  13. 

Taiu.k  to.  /raw  and  past*  wrized  milk  cheat  {lott  3D  and  4D)  stored 

in  warm  room  ai  Madison. 

LOT  Ml).   M  OBSD    M  '..   H,   1911. 


Date 
made. 

Che 

Mo." 

Total 

Total 
Bra! 

total 

1911. 

* 

May  22 

230 

87 

^: 

22 

86 

R6 

80 

25 

233< ' 

M 

BO 

80  iQ 

M 

83 

84 

29 

234C 

BS 

BS 

86 

June     1 

237 

M 

84 

1 

237C 

SO 

BO 

BO 

2 

80 

81 

80.  S 

2 

B6 

7 

240 

'.»4 

<»4 

84 

7 

240C 

78 

78 

711 

g 

242 

9 

242C 

BS 

13 

243 

80 

13 

243C 

BS 

16 

24S 

87 

38 

B7.  5 

15 

24SC 

85 

16 

?46 

ns 

v7 

16 

87 

u 

86 

LOT  41'  1  l*T.    18.    l'.Ml. 


Jum     18 

*48 

91 

MJ 

81.78 

Ifl 

248C 

BS 

BS 

21 

250 

B8 

B8 

21 

B8 

253 

B8 

B8 

88 

28 

BS 

27 

81 

81. 5 

27 

254C 

BO 

B9 

Bl 

89 

28 

2554 ' 

Jillv      A 

:< 

2881 ' 

B7 

88 

B 

81 

BLS 

B 

Bfl 

10 

10 

261C 

VI 

B7 

38 

11 

84 

84 

84 

11 

88 

B8 

B7 

12 

12 

86 

87.5 

udieatos  raw-milk  cheese. 


CHEESE   CURED   IN    COLD   STORAGE. 


85 


CHEESE   CURED   IN    COLD   STORAGE. 

Lot  J^E.— Since  much  of  the  cheese  made  by  the  ordinary  process 
is  put  into  cold  storage  at  about  34°,  and  most  cheese  dealers  have 
cold-storage  warehouses,  a  study  was  begun  of  the  effect  of  cold 
storage  on  pasteurized-milk  cheese.  The  milk  supply  was  so  short 
at  the  time  thai  raw-milk  cheese  could  be  made  on  only  a  few  days. 
Six  or  seven  pasteurized-milk  cheeses  were  made  in  one  vat  each  day 
and  placed  in  the  curing  room  at  Madison,  and  single  cheeses  were 
shipped  to  a  cold-storage  warehouse  at  Waterloo,  Wis.,  at  different 
ages.  Alter  about  three  months  the  cheese  was  all  shipped  back  to 
Madison  in  one  consignment  and  examined  by  the  judges.  One 
ch>ese  from  each  day's  make  was  kept  at  Madison  during  the  entire 
period 

Table  44. — Scores  of  pasteurized  and  raw  milk  cheese  (lot  4E)  put  into  cold  storage  at 
different  ages  and  scored  Oct.  SO,  1911. 


Age 
when 
stored. 

Scored  by  U.  S. 
Baer. 

Scored  by  A.  T. 
Bruhn. 

Average  score. 

Date 
made. 

Cheese 
No.' 

Flavor. 

Tex- 
ture. 

Total. 

Flavor. 

Tex- 
ture. 

Total. 

Flavor. 

Tex- 
ture. 

Total. 

1911. 

July      20 
20 

264.1 

42.00 

28.00 

95.00 

42.  50 

27.00 

94.50 

42.25 

27.50 

94.75 

264.2 

i  day.... 

41.00 

26.50 

92.50 

40.50 

27.00 

92.50 

40.  75 

26.75 

92.50 

20 

264.  .3 

1  week . . 

40.00 

26.00 

91.00 

40.  50 

27.00 

92.50 

40.25 

26.50 

91.75 

20 

264.4 

2  weeks. 

41.00 

28.00 

94.00 

41.00 

27.50 

93.50 

41.00 

27.75 

93.75 

20 

264.5 

4  weeks. 

41.00 

28.00 

94.00 

42.00 

28.00 

95.00 

41.50 

28.00 

94.50 

20 

264.6 

6  weeks. 

41.00 

28.00 

94.00 

42.00 

27.50 

94.50 

41.50 

27.75 

94.25 

20 

265.1 

41.00 

27.00 

93.00 

41.00 

26.50 

92.50 

41.00 

26.75 

92.75 

21 

265.2 

1  day 

40.00 

27.00 

92.00 

41.00 

26.50 

92.50 

40.50 

26.75 

92.25 

21 

265.3 

1  wTeek . . 

42.00 

28.00 

95.00 

42.00 

28.00 

95.00 

42.00 

28.00 

95.00 

21 

265.4 

2  weeks. 

40.  00 

27.00 

92.00 

40.00 

27.00 

92.00 

40.00 

27.00 

92.00 

21 

265.5 

4  weeks. 

40.00 

27.00 

92.00 

40.00 

27.00 

92.00 

40.00 

27.00 

92.00 

21 

265.  6 

4  weeks. 

40.  00 

27.00 

92.  00 

41.00 

27.00 

93.00 

40.50 

27.00 

92.50 

25 

265.7 

6  weeks. 

41.00 

28.00 

94.00 

42.00 

27.00 

94.00 

41.50 

27.50 

94.00 

25 
25 

267.1 
267.2 

41.00 
40.00 

28.00 
26.00 

94.00 
91.00 

42.00 
40.00 

27.00 
26.00 

94.00 
91.00 

41.50 
40.00 

27.50 
26.00 

94.00 
91.00 

1  day  — 

25 

267.3 

1  week . . 

41.50 

27.00 

93.00 

41.50 

27.50 

94.00 

41.50 

27.25 

93.75 

25 

267.4 

2  weeks. 

40.00 

27.00 

92.00 

41.00 

27.00 

93.00 

40.50 

27.00 

92.50 

25 

267.5 

4  weeks. 

41.00 

27.00 

93.00 

40.  50 

27.00 

92.50 

40.75 

27.00 

92.75 

25 

267.6 

6  weeks. 

42.00 

27.00 

94.00 

42.00 

27.  50 

94.50 

42.00 

27.25 

94.25 

25 

267C1 

36.00 

26.00 

87.00 

36.00 

26.50 

87.50 

36.00 

26.25 

87.25 

25 

267C2 

1  day 

38.00 

27.00 

90.00 

39.00 

27.00 

91.00 

38.50 

27.  00 

90.50 

25 

267C3 

2  weeks. 

38.  00 

27.00 

90.00 

38.  50 

27.00 

90.50 

38.25 

27.00 

90.25 

27 
27 

269.1 
269.2 

40.00 
40.  00 

27.00 
27.00 

92.00 
92.00 

41.00 
40.50 

26.50 
26.50 

92.50 
92.00 

40.50 
40.25 

26.75 
26.75 

92.25 
92.00 

1  day 

27 

269.3 

1  week . . 

40.00 

27.00 

92.00 

40.50 

26.50 

92.00 

40.25 

26.  75 

92.00 

27 

269.4 

2  weeks. 

41.00 

27.00 

93.00 

40.00 

26.50 

91.50 

40.50 

26.75 

92.25 

27 

269.5 

4  weeks. 

41.00 

27.00 

93.00 

42.00 

27.00 

94.00 

41.50 

27.00 

93.50 

27 

269.6 

6  weeks. 

42.50 

28.00 

95.50 

42.50 

27.50 

95.00 

42.50 

27.75 

95.25 

27 

269C1 

2  weeks. 

34.00 

23.00 

82.00 

32.00 

25.00 

82.00 

33.00 

24.00 

82.00 

Aug.       1 

1 

272.1 
272.2 

35.00 
36.00 

23.00 
25.00 

83.00 
86.00 

36.00 
36.00 

25.00 
25.00 

86.00 
86.00 

35.50 
36.00 

24.00 
25.00 

84.50 
86.00 

1  day.... 

1 

272.3 

1  week.. 

37.00 

25.00 

87.00 

39.00 

24.00 

88.00 

38.00 

24.  50 

87.50 

1 

272.4 

2  weeks. 

38.00 

25.00 

88.00 

38.00 

25.00 

88.00 

38.00 

25.00 

88.00 

1 

272.5 

4  weeks. 

35.00 

25.00 

85.00 

36.00 

24.00 

85.00 

35.50 

24.  50 

85.00 

1 

272.6 

6  weeks. 

37.00 

24.50 

86.50 

38.00 

25.00 

88.00 

37.50 

24.  75 

87.25 

8 
8 

276.1 
276.2 

37.00 
40.00 

25.00 
26.00 

87.00 
91.00 

39.00 
40.00 

26.00 
26.00 

90.00 
91.00 

38.00 
40.00 

25.50 
26.00 

88.50 
91.00 

*i  day.'.'.". 

8 

276.3 

1  week.. 

40.00 

25.00 

90.00 

39.50 

25.50 

90.00 

39.75 

25.25 

90.00 

8 

276.4 

2  weeks. 

40.00 

24.00 

89.00 

39.00 

25.00 

89.00 

39.50 

24.50 

89.00 

8 

276.5 

4  wreeks. 

40.00 

27.00 

92.00 

39.50 

26.50 

91.00 

39.75 

26.75 

91.50 

22 
22 

283.1 
283.2 

41.00 
40.00 

27.00 
26.00 

93.00 
91.00 

41.50 
40.50 

26.50 
26.00 

93.00 
91.50 

41.25 
40.25 

26.75 
26.00 

93.00 
91.25 

i  day.... 

22 

283.3 

1  week.. 

42.00 

27.00 

94.00 

41.00 

27.00 

93.00 

41.50 

27.00 

93.50 

22 

283.4 

2  weeks. 

40.50 

27.00 

92.50 

41.00 

26.50 

92.50 

40.75 

26.75 

92.00 

22 

283.5 

4  weeks. 

42.00 

27.00 

94.00 

41.50 

27.00 

93.50 

41.75 

27.00 

93.50 

22 

283.6 

42.00 

27.00 

94.00 

42.00 

26.50 

93.50 

42.00 

26.75 

93.75 

»  "C"  in  this  column  indicates  raw-milk  cheese. 


86 


OHEDDAH    I'HKKSK     r'lio.M     I'ASTKT  HI/.KD    MIIK. 


In  everj  case  the  pasteurized-milk  oheese  put  into  coW  Btorage  at 
the  age  of  one  da\  was  criticized  by  the  judges  as  being  Hat,  Low,  and 
not  developed  in  flavor,  and  the  texture  was  described  as  curdy,  new, 
not  broken  down,  not  cured,  etc.  Thej  received  an  average  Bcore 
of  90.84,  as  shown  in  Table  1 1. 

Tin-  cheeses  put  into  cold  storage  at  the  ageof  one  week  received 
an  average  score  of  91.93.  They  were  found  to  be  well  cured,  and 
they  had  Less  mold  on  the  Burface  (practically  none,  both  when  put 
into  Btorage  and  when  taken  out,  than  any  of  the  later  lots.  The 
cheeses  put  into  storage  al  two  weeks,  four  weeks,  and  six  weeks  of 
age  were  given  average  scores  of  91.36,  91.82,  and  91.46,  respectively, 

While  those   kept    at    Madison   for  the  entire  period   BCOred  91.39. 

So  far  as  this  short  series  indicate-,  there  is  no  objection  to  putting 
pasteurized-milk  cheese  into  Btorage  at  :i4°,  at  the  age  <>f  one  week, 
immediately  after  paraffining.     Jt  was  planned,  however,  to  make  a 

more  extensive  trial  of  the  use  of  cold  Btorage  for  pasteurized-milk 
cheese  during  the  season  of  L912. 

BXCEFTIONAX   DirFBRBMCSfl    BETWEEN    nil.    raw    a\i>   PASTEURIZED   MILK   cm 

It  is  of  interest  to  collect  in  one  place  all  of  the  cases  recorded  in 

the  tables  where  the  pasteurized-milk  cheese  was  scored    lower  than 
the  raw,  in  order  if  possible  to  locate  the  cause  for  such  difference. 

Table  45.     Summary  of  cases  in   which  rau-mill;  cheese  scored  higher  than  pasteurized. 


LotslA,2A,SA,4A. 

LotslB,2B,3B.4B. 

Lots  81 

Lot-  3D,  4D. 

Total 

No.' 

Total 

Score. 

Cheese 
No.' 

Total 

Cheese 
No.i 

171 

•171C 

172 

•  172( 

177 

•  177C 

183 

»183C 

184 

L84C 

188 

1  i  w  ' 

•  260C 

261 
MIC 

81.00 
87.00 
81.00 
83.00 
86.00 

79.00 

85.50 
84.50 
83.50 
7S.50 
80.00 
81.50 
85.00 
81  00 

17.' 
1720 

177 
177C 

183 

'-  184C 
188 

l.SNC 

261 
261C 

91.75 
89.00 

91.25 
91.78 

92.00 
92.75 
94.50 
90.50 
91.75 
87  50 
90.25 
90.00 



an 

«  261 C 

Jul 
»261C 

S5.50 
85.00 
88.00 

i  "(••  Indicates  raw-milk  cheese. 

■  These  are  the  cases  hi  which  the  raw-mil]  red  higher  than  the  pasteurized.    The  other  scores 

of  duplicate  cheese  in  the  other  lots  are  given  for  comparison. 


'Hie  fact  thai  pasteurized  and  raw  cheese  from  the  same  milk  may 
occasionally  Bcore  exactly  alike  or  nearly  alike  would  appear  to  indi- 
cate that  where  the  milk  supply  is  excellent  the  quality  of  cheese  pro- 
duced is  not  unproved  by  the  new  process.  With  so  small  a  differ- 
ence m  score  as  half  a  point,  occurring  in  No.  184  in  lot  A  and  No. 


DISCUSSION    el    en  BESE   S<  DEES.  5" 

177  in  lot  B,  it  is  doubtful  whether  bhere  was  anj  difference  betwees 
the  two  cheeses  which  could  be  ascribed  with  certainty  to  the  effect 
of  the  pasteurization  process. 

The  most  adverse  criticism  on  the  process  that  can  be  based  upon 

the  LO  cases  tabulated  above  is  the  following:  It  is  entirely  possible 
that  sonic  harmful  bacteria  or  their  enzvms  which  are  occasionally 
present  in  dirty  milk  may  not  be  destroyed  by  the  pasteurization 
process  and  that  such  infections  damage  the  quality  of  pasteurized- 
milk  cheese  as  well  as  raw-milk  cheese.  In  this  year's  work  it  has 
been  noticed  that  on  a  few  occasions  when  the  raw  milk  was  very  ripe 
the  quality  of  cheese  produced,  even  after  pasteurization,  was  not  so 
good  as  from  milk  of  fairly  good  quality.  For  example:  The  poorest 
pi  steurized-milk  cheese  in  Table  45  is  No.  261,  and  the  milk  used  for 
making  this  was  of  0.28  per  cent  acidity  before  pasteurization.  In 
Table  44,  showing  the  scores  of  cheese  shipped  to  cold  storage,  Nbs. 
272  and  276  are  the  poorest  in  quality  and  these  were  made  from  milk 
which  titrated  0.275  and  0.31  per  cent  acidity,  respectively,  before 
pasteurization.  Of  course  such  milk  should  not  be  accepted  at  any 
cheese  factory. 

No  claim  is  made  that  the  pasteurization  process  is  a  cure  for  all 
the  troubles  of  the  cheese  factory,  or  that  it  reduces  the  responsibility 
resting  on  factory  patrons  to  improve  the  sanitary  quality  of  their 
milk.  It  would,  in  fact,  be  most  unfortunate  if  any  process  could 
be  used  for  making  cheese,  or  any  other  article  of  food,  which  would 
relieve  the  milk  producer  or  the  factory  man  of  the  necessity  for 
cleanliness. 

SUMMARY    OF    DISCUSSION    OF    SCORES. 

The  scores  of  lots  IB,  2B,  3B,  and  4B,  3C  and  4C,  and  3D  and  4D 
all  show  that  cheese,  either  raw  or  pasteurized,  stored  for  one  or  two 
months  at  about  80°  are  often  seriously  injured,  so  as  to  be  unsalable 
at  the  ruling  market  price.  The  pasteurized  cheese  came  out  of 
such  storage  better  in  quality  than  the  rawvmilk  cheese  in  about  90 
per  cent  of  all  the  cases  observed.  It  is  clear  that  pasteurized-milk 
cheese  is  better  suited  to  stand  exposure  to  high  temperature  than 
raw-milk  cheese.  This  fact  may  find  useful  application  in  two  ways: 
While  it  is  never  advisable  to  store  market  cheese  for  any  great 
length  of  time  in  the  South,  yet  several  days  or  weeks  may  often 
elapse  before  cheese  shipped  South  is  finally  sold  to  the  consumer, 
and  it  appears  that  pasteurized-milk  cheese  should  stand  this  ex- 
posure with  less  damage  in  quality  than  raw-milk  cheese.  It  is 
likely,  too,  that  pasteurized-milk  cheese  can  be  cured  at  ordinary 
curing-room  temperatures  below  70°  in  Wisconsin  without  the  use 
of  ice  or  mechanical  refrigeration,  thus  avoiding  part  of  the  expense 
for  cold  storage.  The  quality  of  the  53  raw-milk  cheeses  in  lots  1A, 
2 A,  3 A,  and  4A,  cured  at  60°  to  73°  at  Madison,  is  represented  by  the 


CHBDDAB  OHBBSB    ii;<»m    PAfl  I  i.l'iil/l.D   MILK. 

average  total  score  of  89.09,  and  would  no  doubt  have  been  greatly 
improved  if  the  cheese  bad  been  cured  in  cold  storage.  In  51  i 
out  of  53  the  pasteurized-milk  cheese  In  these  lots  scored  lugher 
khan  the  raw,  on  the  average  3.8  points  higher,  the  average  total 
score  of  the  pasteurized  being  92.76  points,  which  indicates  that  cold 
storage  for  the  pasteurized  cheese  was  not  necessary. 

In  a  short  series  of  cheese  placed  in  cold  Btorage  at  34°  F.  at  dif- 
ferent ages,  it  was  found  that  those  stored  at  the  age  <»f  one  day  were 
CUrdy  and  uncured  at  the  age  Of  three  months,  while  those  placed  in 
Btorage  at  the  age  Of  one  week  were  free  from  this  fault  and  scored 
as  high,  even  a  little  higher,  and  showed  les^  mold  on  the  surface 
than   those  put   in  storage  when  older  than  one  week.      From  this  it 

appears  that  pasteurized-milk  cheese  can  he  safely  put  in  cold  Btorage 

at  the  age  of  one  week  immediately  aft  or  paraffining.     It  was  planned 

to  try  cold  storage  with  hoth  raw  and  pasteurized-milk  cheese 
during  1912. 

THE    DEMAND   FOR   PASTEURIZED-MILK   CHEESE. 

One  of  the  objects  of  the  work  during  1909,  1910,  and  1911  was  to 
sell  the  cheese  to  consumers  as  widely  as  possible,  and  learn  whether 

it  WOUld  meet  with  favor  and  continued  demand.  It  was  felt  neces- 
sary thus  to  establish  its  suitability  for  the  market  before  recom- 
mending cheese  makers  to  take  up  the  new  process. 

The  amount  of  pasteurized-milk  cheese  sold  each  year  was  limited 
by  the  output  of  the  factory,  it  being  impossible  to  secure  a  larger 
supply  of  milk.  Much  more  cheese  could  have  been  sold  to  the 
same  purchaseis.  and  doubtless  to  others,  if  we  had  had  the  cheese 
to  sell.  In  nearly  all  cases  the  cheese  was  sold  at  the  current  price 
ruling  on  the  Plymouth  cheese  board,  f.  o.  b.  Madison  without 
discount.  During  1910.  4.S15J  pounds  of  pasteurized-milk  cheese 
valued  at  $711.1(3  were  sold  to  19  representative  grocery  stores. 
hotels,  restaurants,  and  delicatessen  stores  in  Madison.  Wis.  The 
total  number  of  such  sales  was  137  during  the  season.  Nearly 
every  purchaser  reordered  it  several  times,  and  three  of  the  leading 
retailers  reordered  it  15.  20,  and  49  times,  respectively,  during  the 
season.  The  average  price  paid  for  all  of  this  cheese  was  14J  cents 
per  pound.  During  1900,  1911).  and  1911,  41  shipments  of  pasteur- 
ized-milk cheese  weighing  10,126  pounds  in  all  and  valued  at  $1,382.93 
were  sent  to  27  leading  cheese  dealers,  including  a  few  retail  store-, 
at  New  York,  Boston,  Philadelphia,  Chicago,  St.  Louis.  Minneapolis, 
and    San    Francisco,    and    at    various    Wisconsin    points    outside    of 

Madison,  including  Plymouth,  Sheboygan,  Fond  du  Lac  Marshfield, 

Richland  Center.  Waterloo,  and  Milwaukee.  Samples  of  the  cheese 
were  also  Bhipped  to  expeiiment  station  workers  in  the  leading  dairy 
States  for  an  examination. 


EXTRA   COST   OF   PASTEURIZED  Mil  K    CIIKESE.  89 

OPINIONS   OF   PURCHASERS. 

No  written  opinions  were  asked  from  dealers  in  Madison  handling 
the  pasteurized-milk  cheese,  neither  were  they  urged  bo  purchase  a 

second    time.     The    university    delivery    wagon    making    two    t rips 

daily  among  retail  stores  took  such  orders  as  were  given.  The  fact 
that  a  dealer  bought  this  make  of  cheese  only  once  may  be  due  to  a 
variety  of  causes,  such,  for  example,  as  business  relations  with  other 
wholesale  cheese  dealers  in  the  city.  The  fact  that  several  of  the 
leading  grocers  sold  tins  cheese  continuously  for  several  months  and 
repurchased  it  every  week  or  oftener,  and  always  without  reporting 
any  complaint  from  consumers,  is  taken  to  indicate  that  it  was 
satisfactory  to  the  retail  trade  of  this  city. 

An  effort  was  made  to  obtain  a  written  opinion  from  every  firm 
outside  of  Madison  to  whom  the  cheese  were  sold.  It  was  usually 
impossible  to  send  many  shipments  to  a  single  purchaser,  because 
it  was  desired  to  distribute  the  available  supply  of  cheese  as  widely 
as  possible. 

The  letters  received  from  dealers  outside  of  Madison  show  that  all 
except  a  very  few  found  the  cheese  to  be  entirely  satisfactory,  and 
salable  at  the  full  market  price.  Here  again  the  occasional  disap- 
proval of  a  cheese  may  be  due  to  an  oversupply  in  the  buyer's  ware- 
house, or  other  causes  than  the  quality  of  the  cheese  iteslf.  It  is 
interesting  to  note  that  pasteurized-milk  cheese  shipped  to  two  firms 
who  apparently  disliked  it  was  the  same  day's  make  as  others  shipped 
on  the  same  date  to  three  other  firms  who  praised  their  quality  and 
pronounced  them  satisfactory.  In  every  case  dealers  were  informed 
that  the  cheese  "was  made  by  special  process,  which  we  are  trying 
at  Madison,  by  which  it  is  hoped  that  cheese  of  cleaner  flavor  and 
greater  uniformity  can  be  obtained. "  In  no  case  were  dealers  in- 
formed as  to  the  nature  of  the  process  or  that  the  milk  was  pasteur- 
ized. The  purpose  was  to  excite  the  dealers'  interest  and  secure 
careful  examination  of  the  cheese,  unqualified  by  any  prejudice  for 
or  against  pasteurization. 

The  very  general  expression  of  approval  of  the  product  in  the  let- 
ters from  dealers  and  experiment  stations  appears  to  warrant  fur- 
ther trial  of  the  method  on  a  larger  scale  than  heretofore. 

THE    EXTRA    COST    OF    MAKING    PASTEURIZED-MILK    CHEESE. 

While  it  has  been  shown  that  an  increased  yield  of  cheese  is  ob- 
tained there  are  also  additional  costs,  which  must  be  charged  agamst 
the  cheese  made  by  this  method.  Such  costs  will  include  the  interest 
on  investment,  and  depreciation,  of  a  pasteurizer,  cooler,  and  receiv- 
ing vat,  a  charge  for  the  hydrochloric  acid  used  and  for  the  expense 
of  steam  heat  and  power  for  pumping  water  for  cooling  the  pasteur- 
ized milk,  and  for  running  the  pasteurizer. 


'.ill  OHEDDAB   CHBS8E    PROM    PASTEURIZED    MH.K. 

Preliminary  estimates,  based  upon  available  data,  seem  to  indicate 
that  ilif  extra  cost  of  making  pasteurized  milk  cheese  is  less  than  the 

additional  value  of  the  cheese,  Leaving  a  net   profit   from  tlic  1186  of  the 

process,  as  compared  with  the  regular  factory  process.  Since  the 
Bteam  and  water  supplies  used  in  the  work  at  Madison  were  drawn 
from  the  general  Bervice  pipes  of  the  Wisconsin  Agricultural  Experi- 
ment  Station  it  was  impossible  to  determine  these  items  of  cost  with 
exactness. 

In  order  to  ascertain  precisely  what  the  charges  for  Bteam  heat. 

power,   etc.   are   at    an   average  cheese   factory   in    Wisconsin,   a  c.  m- 

plete  ontlit  for  making  pasteurized-milk  cheese  will  he  Bet  up  at  a 
country  cheese  factory,  easily  accessible  from  Madison,  and  operated 
1>\  an  experienced  and  successful  cheese  maker.  Cheese  will  be  made 
there  by  both  the  regular  factory  method  and  by  the  new  method  in 
order  to  ascertain  more  fully  the  cost  of  making,  the  increased  yield, 

and  the  market   value  of  pasteurized-milk  cheese. 

FUETHEB    TRIALS    OF    THE    NEW    PROCESS    IN    <  EEESE    I  A<    M>i:h 

The  results  described  in  this  bulletin  appear  to  indicate  that  the 
new  method  of  cheese  making  is  an  improvement  over  the  regular 
process  now  commonly  used.  Working  with  the  milk  supply  avail- 
able at  Madison,  the  new  method  is  unquestionably  an  improvement 
over  the  old.  It  is  a  fact  well  known  to  cheese  makers,  however,  that 
the  milk  supplies  found  at  different  factories  d<>  not  always  behave 
alike  in  the  cheese  vat,  so  that  the  old  process  must  frequently  be 
modified  to  suit  the  conditions  encountered  in  different  Localities.  It 
remains,  therefore,  to  test  the  new  method  at  several  factories  in  dif- 
ferent cheese-making  districts  before  it  can  be  recommended  for  use 
generally.  Cheese  maker-  are  advised  to  await  the  publication  of 
results  of  further  trials  before  undertaking  to  use  the  new  method  on 
a  commercial  scale. 

It  is  hoped  that   the  new  method  will  receive  careful  attention  and 

criticism  by  such  cheese  experts  at  experiment  stations  in  different 

parts  of  the  country  as  may  be  able  to  give  it  a  trial.  The  authors 
will  be  glad  to  correspond  with  any  one  interested  and  to  aid  in  such 
trials  so  far  as  circumstances  permit. 

SUMMARY. 

l'hlilMlNAKY    AND    COMPARATIVE     WORE     Willi     THE    OLD    AND    NEW 

M  LTHODS. 

The  continued  improvement  of  the  cheese-making  industry  calls  for 
more  economical  factory  management.     Large,  well-equipped  facto- 
ries should  replace  many  of  the  small,  poorly  supported  factorii 
the  present  time. 


SUMMARY.  91 

To  enable  cheese  factories  to  handle  milk  from  larger  areas  of  ter- 
ritory, and  for  other  reasons  also,  a  new  method  of  cheese  making  is 
needed  by  means  of  which  milk  of  variable  quality  from  inan\  farms 
can  (1)  be  brought  into  practically  uniform  condition  for  cheese 
making  at  the  factory,  and  (2)  can  be  made  up  into  cheese  in  a  uni- 
form, routine  manner  daily  without  variations  of  time  or  method  of 
handling;  also  (3)  cheese  of  greater  uniformity  should  be  produced. 
and  (4)  the  losses  in  yield  and  quality  of  cheese  due  to  defective  milk, 
now  common  in  factories,  should  be  avoided. 

During  the  years  1905  and  1906  experimental  cheese  was  made 
without  starter,  adding  in  its  place  to  the  raw  milk  some  commercial 
acid,  as  hydrochloric  acid  or  other  kinds.  The  method  of  adding  the 
acid  to  milk  was  perfected,  and  a  two  weeks'  trial  of  the  process  was 
finally  made  in  a  commercial  factory  at  Muscoda,  Wis.  It  was  show  n 
clearly  that  the  addition  of  hydrochloric  acid  to  milk  in  a  cheese  fac- 
tory is  entirely  practicable  and  that  the  quality  of  the  cheese  is  not 
in  any  way  injured  by  such  addition,  but  it  was  also  found  that  the 
quality  of  cheese  obtained  from  overripe  or  tainted  milk  was  no  bet- 
ter than  by  the  use  of  the  ordinary  factory  methods.  Therefore, 
there  was  no  reason  for  recommending  the  use  of  hydrochloric  acid  to 
cheese  makers  at  that  time. 

Most  of  the  defects  observed  in  cheese-factory  milk  are  of  bacterial 
origin,  and  in  other  branches  of  the  dairy  industry  pasteurization  is 
successfully  employed  to  overcome  these  faults.  The  desirability 
of  pasteurizing  milk  for  cheese  making,  if  possible,  has  often  been 
pointed  out. 

In  1907  a  few  lots  of  milk  were  pasteurized  in  a  discontinuous 
pasteurizer  and  acidulated  with  hydrochloric  acid,  and  the  cheese 
obtained  was  such  as  to  demonstrate  the  importance  of  further 
study. 

In  1908  equally  good  results  were  obtained  by  use  of  the  contin- 
uous pasteurizer.  A  temperature  of  160°  to  165°  was  decided  upon 
as  being  sufficiently  high  to  effectually  check  bacterial  action  in 
milk  for  cheese-making  purposes.  Bacterial  counts  showed  that 
over  99  per  cent  of  the  total  bacterial  content  of  the  milk  was  de- 
stroyed at  this  temperature.  The  use  of  higher  temperatures  was 
shown  to  be  objectionable  on  account  of  the  effect  upon  the  quality 
of  the  cheese. 

In  1909  cheese  was  made  almost  daily  both  by  the  regular  factory 
process  and  by  the  new  process  from  pasteurized  milk.  The  regular 
milk  supply  was  thoroughly  mixed  each  day  and  divided  into  two 
lots  for  the  two  different  processes.  The  cheese  made  from  pasteur- 
ized milk  was  found  after  curing  to  be  cleaner  in  flavor  and  superior 
in  texture  to  the  raw-milk  cheese.  The  difference  was  more  marked 
the  poorer  the  quality  of  the  milk  supply.  Many  of  the  details  of 
the  process  were  studied  and  improved. 


92  OHEDDAB   CHEESE    PBOM    PASTEURIZED   MILK. 

In  1910  the  making  of  cheese  by  the  two  methods  for  comparison 
was  continued,  and  the  emir*'  output  of  pasteurized-milk  cheese  was 
Bold  to  retail  grocers,  mostly  in  the  city  <>f  Madison,  in  order  to 
determine  bo*   tins  cheese  would  suit  the  trade.    The  cheese  met 

With    read}    and    continued    sale.       It    w.is   noticed    also    that    the   yield 

of  cheese  was.  regularly,  somewhat  greater  by  the  new  process  than 
l>\  the  old. 

In  mil  better  facilities  were  provided  for  weighing  Large  quan- 
tities of  milk  and  cheese  (juieklv  and  accurately,  and  the  yields  of 
cheese  obtained  from  raw  and  pasteurized  milk  were  carefulU  de- 
termined. The  accuracy  of  the  experimental  methods  was  such 
that  in  making  duplicate  vats  of  cheese  from  pasteurized  milk  the 
yields  differed  l>y  only  0.58  per  cent  on  the  average.  A  greater 
yield  of  cheese  was  always  obtained  from  the  pasteurized  milk  than 
from  law  milk,  and  during  the  year  1911  the  average  ,Lrain  in  yield 
of  green  cheese  was  ">.:;7  per  cent.  However,  the  green  pasteurized- 
milk  cheese  shrank  a  little  more  than  the  raw-milk  cheese,  BO  that 
when  paraffined  the  average  gain  in  yield  from  pasteurized  milk  was 
4.76  per  cent.  After  curing  cheese  at  60°  to  70°  F.  for  about  loo 
days,  the  gain  in  yield  of  pasteurized-milk  cheese  over  tin-  raw  was 
4.22  per  cent. 

SOME  ADVANTAGES  FROM  THE  USE  OF  PASTEl'lM/ED  MILK  AND  HYDRO- 
CHLORIC  ACID. 

The  average  loss  of  fat  in  whey  from  pasteurized-acidulated  milk 
is  about  <U7  per  cent  measured  at  the  time  the  whey  is  drawn  from 
the  vat.  This  is  less  than  hall"  the  loss  in  average  factories  using 
raw  milk.  The  total  Joss  of  fat  in  whey  and  drippings  from  vat  and 
pic--,  using  pasteurized  milk  with  acid,  averaged  1.58  per  cent  of  the 
weight  of  the  cheese,  or  less  than  one-half  of  the  usual  loss  in  han- 
dling raw   milk. 

In  addition  to  this  saving  of  fat,  it  is  found  that  a  somewhat  larger 
proportion    of   moisture   can    be   incorporated    in    pasteurized-milk 

cheese    than    in    ordinary    cheese,    without    damage    to    the    quality. 

The  gain  in  the  yield  of  pasteurized-milk  cheese  is  tine  partly  t<»  fat 
and  partly  to  moisture. 

Scores  and  criticisms  made  by  Competent  cheese  judges  show- 
that  the  pasteurized-milk  cheese  varies  less  in  quality  and  averages 
better  by  3.7  points  of  total  score  than  the  raw-milk  cheese  made 
from  portions  <d*  the  same  milk  supply.      In  96  per  cent   of  all  cases 

the  pasteurized-milk  cheese  Bcored  higher  than  the  raw-milk  cheese. 
Duplicate  >ets  of  cheese  were  cured  at  New  Orleans  for  one  month 
at  70  to  83  (monthly  average  Bgures  during  the  summer),  and  here 
the  raw  milk  Lost  more  in  weight  than  the  pasteurized,  so  thai  the 
average  gain  in  yield  of  pasteurized  over  raw  rose  to  6.21  per  cent. 


OUTLINE   OF    THE    NEW    METHOD.  93 

From  other  cheese  cured  at  Madison  on  tin  pans  in  a  warm  room,  it 
was  Learned  that  the  raw-milk  cheese  lost  considerable  amounts  of 

fat  at  75°  to  85°  while  the  pasteurized-milk  cheese  lost  none. 

Storage  for  a  month  at  an  average  temperature  of  75°  to  80°  at 
New  Orleans  is  not  recommended  for  any  cheese,  yet  it  was  found 
that  pasteurized-milk  cheese  averaged  3  to  8  points  better  in  total 
score  after  such  storage  than  raw-milk  cheese. 

Since  pasteurized-milk  cheese  can  be  cured  without  injury  at  70°, 
it  is  likely  that  in  most  cases  the  expense  of  cold  storage  for  this 
cheese  can  be  avoided. 

Pasteurized-milk  cheese  can  be  put  into  cold  storage  at  34°  at  the 
age  of  one  week  and  possibly  earlier  without  injury.  The  earlier 
the  cheese  can  be  put  in  storage,  if  this  is  done  afc  all,  the  greater  will 
be  the  gain  in  yield  by  the  new  process.  It  is  planned  to  study  the 
cold  storage  of  this  cheese  further. 

During  1910-1911  about  $2,100  worth  of  pasteurized-milk  cheese 
was  sold  to  about  50  dealers,  both  wholesale  and  retail,  in  various 
large  cities  from  New  York  to  San  Francisco.  The  cheese  sold 
readily  for  the  ruling  market  prices  and  often  above.  Very  few 
dealers  offered  any  objections  to  them  and  several  wished  to  buy 
them  regularly.  A  good  many  were  sold  throughout  the  South  by 
dealers.  In  general,  the  cheese  passed  through  the  market  without 
exciting  special  comment,  selling  for  full  price  and  giving  satisfaction. 
They  were  not  labeled  or  marked  except  with  a  number  for  purposes 
of  identification.  There  appears  to  be  no  reason  why  pasteurized- 
milk  cheese  can  not  be  sold  regularly  in  any  market  with  entire 
satisfaction,  excepting  possibly  to  the  limited  trade  that  demands 
very  high-flavored  cheese. 

OUTLINE  OF  THE  NEW  METHOD. 

In  the  method  here  described  a  principle  is  applied  to  the  cheese- 
making  process  which  has  already  been  found  useful  in  many  other 
lines  of  manufacture,  namely : 

The  raw  material,  milk,  is  first  treated  by  a  preparatory  process 
to  bring  it  into  uniform  condition  before  it  enters  the  manufacturing 
process  proper.  Material  of  uniform  quality  thus  prepared  is  made 
up  into  the  finished  product  by  a  uniform  routine  process  without 
daily  variations  of  the  time  schedule  or  other  details,  and  the  product 
is  more  uniform  in  quality,  has  better  keeping  qualities,  etc.,  than 
the  product  obtained  by  the  older  process. 

The  difficulties  met  with  hitherto  in  making  American  Cheddar 
cheese  from  pasteurized  milk  are: 

First.  That  heated  milk  coagulates  poorly  with  rennet;  and 

Second.  The  curd  when  obtained  does  not  expel  moisture  pre- 
cisely as  a  raw-milk  curd  does,  and  this  effect  is  more  marked  the 


9  1  OHEDDAB   0HBB8B   FROM   PASTEURIZED   MILK. 

higher  the  temperature  of  pasteurization.  The  quality  and  behavior 
of  pasteurized-milk  curd  Buggest  that  it  Lacks  the  acid  which  is 
normally  produced  in  raw-milk  curds  by  the  action  of  bacteria  on 
milk  sugar. 

The  first  of  these  difficulties,  but  not  the  second,  can  be  over- 
come by  adding  calci um-chlorid  solution  to  pasteurized  milk.  This 
method  has  been  tried  experimentally,  hut  is  not  recommended  for 
use  m  American  cheese  factories.  Both  difficulties,  however  are  over- 
came by  adding  an  acid,  preferably  hydrochloric,  to  the  pasteurized 
milk.  Hydrochloric  acid  Lb  normally  present  in  the  human  stomach 
during  the  process  of  digestion  in  larger  proportions  than  that  added 
to  milk  in  this  pi  cheese  making.     Further,  95  per  cent  of  the 

added  acid  passes  out  of  the  cheese  with  the  whey  during  tin'  process 
of  manufacture.  On  this  account  no  objection  can  he  made  on 
sanitary  grounds  to  the  use  of  this  acid  in  the  manner  and  for  the 
purposes  described. 

Among  different  lots  of  cheese  part  of  winch  was  made  with 
hydrochloric  acid  and  part  with  calcium  ehlorid  added  to  portions 
of  the  same  milk  after  pasteurization,  those  made  with  acid  were 
found  to  he  more  uniform  in  moisture  content  and  superior  both  in 
flavor  and  texture  to  those  made  with  calcium  cldorid.  The  1 
of  fat  in  the  whey  are  reduced  by  the  use  of  the  acid.  Pasteuriza- 
tion and  acidulation  of  milk  for  cheese  making  appear  to  be  com- 
plementary processes.  Used  together  they  furnish  a  means  for 
bringing  milk  daily  into  uniform  condition  both  as  to  acidity  ami 
bacterial  content  for  cheese-making  purposes. 

The  acidulation  of  milk  with  hydrochloric  acid  after  pasteuriza- 
tion is  accomplished  without  difficulty  or  danger  of  curdling  by 
running  a  small  stream  of  the  acid,  of  normal  concentration,  into 
the  cooled  milk  as  it  flows  from  the  continuous  pasteurizer  into 
the  cheese  vat.  One  pound  of  normal-strength  acid  is  sufficient  to 
raise  100  pounds  of  milk  from  0.16  per  cent  to  0.25  per  cent  acidity 
(calculated  as  per  cent  of  lactic  acid).  The  amount  of  acid  needed 
each  day  to  bring  the  milk  up  to  0.25  per  cent  acidity  is  read  from 
a  table  or  calculated  from  the  weight  of  the  milk  and  its  acidity, 
determined  by  the  use  of  Manns's  acid  test  (titration  with  tenth- 
normal sodium  hydrate  and  phenolphthalein).    Tin4  preparation  <>f 

Standard-Strength  acid  in  carboy  lots  for  this  work  and  the  acidula- 
tion of  milk  present  no  great  difficulty  to  anyone  who  is  able  to 
handle  Manns's  acid  test  correctly. 

After  the  milk  is  pasteurized  and  acidulated  three-fourths  per 
cent  of  first-claSS  --tarter  is  added  and  the  vat  is  heated  to  85°.  It 
i-  set  with  rennet,  tiding  2  ounces  of  rennet  per  thousand  pounds 
of  milk,  so  that  the  milk  begins  to  curdle  in  7  minutes  and  is  cut 
with   three-eighth   inch   knives   m   25   minutes.     All   portions  of  the 


OUTLINE   OF   THE    NKW    METHOD.  95 

work  after  adding  rennet  are  carried  out  in  an  unvarying  routine 
manner,  according  to  a  fixed-time  schedule  every  day.  As  booh 
as  the  rennet  has  been  added  the  cheese  maker  is  able  to  calculate 
the  exact  time  of  day  when  each  of  the  succeeding  operations  should 
be  performed,  and  the  work  of  making  the  cheese  is  thus  simplified 
and  systematized.  It  is  possible  that  the  routine  process  here  de- 
scribed may  be  varied  somewhat  with  advantage  at  different  factories. 
For  example,  some  experienced  cheese  makers  may  prefer  to  mat  the 
curds  on  the  bottom  of  the  vat  instead  of  on  racks  or  may  find  the 
use  of  the  "curd  gauge"  unnecessary,  and  local  conditions  may 
be  found  in  different  factories  making  other  adjustments  of  details 
desirable.  However,  the  experience  already  had  with  the  process  indi- 
cates that  the  routine  of  daily  operations  found  suitable  at  any  fac- 
tory can  be  practiced  there  throughout  the  season  without  variation. 

It  is  the  intention  to  give  the  new  process  a  thorough  trial  in 
different  cheese  factories  in  various  localities  to  test  its  applica- 
bility to  different  milk  supplies  before  recommending  it  for  general 
use  by  cheese  makers.  These  trials  will  show  whether  new  diffi- 
culties may  arise  winch  were  not  encountered  heretofore.  Cheese 
makers  are  therefore  advised  to  await  the  publication  of  results  of 
further  trials  of  the  method  by  the  writers  before  undertaking  to 
use  the  new  process  at  their  factories. 

The  extra  cost  of  making  pasteurized-milk  cheese  is  being  studied 
with  a  view  to  finding  out  accurately  what  the  net  profit  is  in  making 
this  cheese  compared  with  the  regular  process. 

The  new  process  should  interest  the  farmer  because  of  the  increased 
yield  and  the  avoidance  of  the  usual  losses  in  yield  and  quality  of 
cheese  due  to  defective  milk.  It  should  interest  the  cheese  maker 
because  the  process  of  making  is  systematized  to  such  a  degree  that 
it  is  conducted  upon  a  fixed-time  schedule  for  all  operations.  It 
should  interest  the  dealer  because  the  cheese  is  more  uniform  in 
quality  and  there  is  less  need  for  cold  storage  in  curing.  Finally, 
the  cheese  should  interest  the  consumer,  because  it  is  more  uniform 
in  flavor  than  most  of  the  cheese  to  be  found  on  retail  counters  and 
because  it  is  made  from  pasteurized  milk  and  is  therefore  a  more 
sanitary  product  than  ordinary  American  cheese  made  from  raw 
milk. 


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UNIVERSITY  OF  FLORIDA 

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3  1262  08928  6537 


